diff --git a/Lib/site.py b/Lib/site.py
index daa56e15894..460269433f0 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -312,6 +312,10 @@ def _getuserbase():
 # Same to sysconfig.get_path('purelib', os.name+'_user')
 def _get_path(userbase):
     version = sys.version_info
+    if hasattr(sys, 'abiflags') and 't' in sys.abiflags:
+        abi_thread = 't'
+    else:
+        abi_thread = ''
 
     implementation = _get_implementation()
     implementation_lower = implementation.lower()
@@ -322,7 +326,7 @@ def _get_path(userbase):
     if sys.platform == 'darwin' and sys._framework:
         return f'{userbase}/lib/{implementation_lower}/site-packages'
 
-    return f'{userbase}/lib/python{version[0]}.{version[1]}/site-packages'
+    return f'{userbase}/lib/python{version[0]}.{version[1]}{abi_thread}/site-packages'
 
 
 def getuserbase():
@@ -390,6 +394,10 @@ def getsitepackages(prefixes=None):
 
         implementation = _get_implementation().lower()
         ver = sys.version_info
+        if hasattr(sys, 'abiflags') and 't' in sys.abiflags:
+            abi_thread = 't'
+        else:
+            abi_thread = ''
         if os.sep == '/':
             libdirs = [sys.platlibdir]
             if sys.platlibdir != "lib":
@@ -397,7 +405,7 @@ def getsitepackages(prefixes=None):
 
             for libdir in libdirs:
                 path = os.path.join(prefix, libdir,
-                                    f"{implementation}{ver[0]}.{ver[1]}",
+                                    f"{implementation}{ver[0]}.{ver[1]}{abi_thread}",
                                     "site-packages")
                 sitepackages.append(path)
         else:
diff --git a/Lib/sysconfig/__init__.py b/Lib/sysconfig/__init__.py
index 98a14e5d3a3..83e057c177f 100644
--- a/Lib/sysconfig/__init__.py
+++ b/Lib/sysconfig/__init__.py
@@ -27,10 +27,10 @@ _ALWAYS_STR = {
 
 _INSTALL_SCHEMES = {
     'posix_prefix': {
-        'stdlib': '{installed_base}/{platlibdir}/{implementation_lower}{py_version_short}',
-        'platstdlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}',
-        'purelib': '{base}/lib/{implementation_lower}{py_version_short}/site-packages',
-        'platlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}/site-packages',
+        'stdlib': '{installed_base}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
+        'platstdlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
+        'purelib': '{base}/lib/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
+        'platlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
         'include':
             '{installed_base}/include/{implementation_lower}{py_version_short}{abiflags}',
         'platinclude':
@@ -77,10 +77,10 @@ _INSTALL_SCHEMES = {
     # Downstream distributors who patch posix_prefix/nt scheme are encouraged to
     # leave the following schemes unchanged
     'posix_venv': {
-        'stdlib': '{installed_base}/{platlibdir}/{implementation_lower}{py_version_short}',
-        'platstdlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}',
-        'purelib': '{base}/lib/{implementation_lower}{py_version_short}/site-packages',
-        'platlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}/site-packages',
+        'stdlib': '{installed_base}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
+        'platstdlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
+        'purelib': '{base}/lib/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
+        'platlib': '{platbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
         'include':
             '{installed_base}/include/{implementation_lower}{py_version_short}{abiflags}',
         'platinclude':
@@ -148,11 +148,11 @@ if _HAS_USER_BASE:
             'data': '{userbase}',
             },
         'posix_user': {
-            'stdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short}',
-            'platstdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short}',
-            'purelib': '{userbase}/lib/{implementation_lower}{py_version_short}/site-packages',
-            'platlib': '{userbase}/lib/{implementation_lower}{py_version_short}/site-packages',
-            'include': '{userbase}/include/{implementation_lower}{py_version_short}',
+            'stdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
+            'platstdlib': '{userbase}/{platlibdir}/{implementation_lower}{py_version_short}{abi_thread}',
+            'purelib': '{userbase}/lib/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
+            'platlib': '{userbase}/lib/{implementation_lower}{py_version_short}{abi_thread}/site-packages',
+            'include': '{userbase}/include/{implementation_lower}{py_version_short}{abi_thread}',
             'scripts': '{userbase}/bin',
             'data': '{userbase}',
             },
@@ -487,6 +487,9 @@ def _init_config_vars():
         # the init-function.
         _CONFIG_VARS['userbase'] = _getuserbase()
 
+    # e.g., 't' for free-threaded or '' for default build
+    _CONFIG_VARS['abi_thread'] = 't' if _CONFIG_VARS.get('Py_GIL_DISABLED') else ''
+
     # Always convert srcdir to an absolute path
     srcdir = _CONFIG_VARS.get('srcdir', _PROJECT_BASE)
     if os.name == 'posix':
@@ -655,6 +658,10 @@ def get_python_version():
     return _PY_VERSION_SHORT
 
 
+def _get_python_version_abi():
+    return _PY_VERSION_SHORT + get_config_var("abi_thread")
+
+
 def expand_makefile_vars(s, vars):
     """Expand Makefile-style variables -- "${foo}" or "$(foo)" -- in
     'string' according to 'vars' (a dictionary mapping variable names to
diff --git a/Lib/test/test_embed.py b/Lib/test/test_embed.py
index 634513ec7a5..30dab1fbaa4 100644
--- a/Lib/test/test_embed.py
+++ b/Lib/test/test_embed.py
@@ -48,6 +48,8 @@ API_ISOLATED = 3
 INIT_LOOPS = 4
 MAX_HASH_SEED = 4294967295
 
+ABI_THREAD = 't' if sysconfig.get_config_var('Py_GIL_DISABLED') else ''
+
 
 # If we are running from a build dir, but the stdlib has been installed,
 # some tests need to expect different results.
@@ -1285,11 +1287,11 @@ class InitConfigTests(EmbeddingTestsMixin, unittest.TestCase):
             ver = sys.version_info
             return [
                 os.path.join(prefix, sys.platlibdir,
-                             f'python{ver.major}{ver.minor}.zip'),
+                             f'python{ver.major}{ver.minor}{ABI_THREAD}.zip'),
                 os.path.join(prefix, sys.platlibdir,
-                             f'python{ver.major}.{ver.minor}'),
+                             f'python{ver.major}.{ver.minor}{ABI_THREAD}'),
                 os.path.join(exec_prefix, sys.platlibdir,
-                             f'python{ver.major}.{ver.minor}', 'lib-dynload'),
+                             f'python{ver.major}.{ver.minor}{ABI_THREAD}', 'lib-dynload'),
             ]
 
     @contextlib.contextmanager
@@ -1343,7 +1345,7 @@ class InitConfigTests(EmbeddingTestsMixin, unittest.TestCase):
             expected_paths = [paths[0], os.path.join(home, 'DLLs'), stdlib]
         else:
             version = f'{sys.version_info.major}.{sys.version_info.minor}'
-            stdlib = os.path.join(home, sys.platlibdir, f'python{version}')
+            stdlib = os.path.join(home, sys.platlibdir, f'python{version}{ABI_THREAD}')
             expected_paths = self.module_search_paths(prefix=home, exec_prefix=home)
 
         config = {
@@ -1384,7 +1386,7 @@ class InitConfigTests(EmbeddingTestsMixin, unittest.TestCase):
             expected_paths = [paths[0], os.path.join(home, 'DLLs'), stdlib]
         else:
             version = f'{sys.version_info.major}.{sys.version_info.minor}'
-            stdlib = os.path.join(home, sys.platlibdir, f'python{version}')
+            stdlib = os.path.join(home, sys.platlibdir, f'python{version}{ABI_THREAD}')
             expected_paths = self.module_search_paths(prefix=home, exec_prefix=home)
 
         config = {
@@ -1515,7 +1517,7 @@ class InitConfigTests(EmbeddingTestsMixin, unittest.TestCase):
             if not MS_WINDOWS:
                 lib_dynload = os.path.join(pyvenv_home,
                                            sys.platlibdir,
-                                           f'python{ver.major}.{ver.minor}',
+                                           f'python{ver.major}.{ver.minor}{ABI_THREAD}',
                                            'lib-dynload')
                 os.makedirs(lib_dynload)
             else:
diff --git a/Lib/test/test_getpath.py b/Lib/test/test_getpath.py
index 2f7aa69efc1..6c86c3d1c8c 100644
--- a/Lib/test/test_getpath.py
+++ b/Lib/test/test_getpath.py
@@ -844,6 +844,7 @@ DEFAULT_NAMESPACE = dict(
     PYDEBUGEXT="",
     VERSION_MAJOR=9,    # fixed version number for ease
     VERSION_MINOR=8,    # of testing
+    ABI_THREAD="",
     PYWINVER=None,
     EXE_SUFFIX=None,
 
diff --git a/Lib/test/test_site.py b/Lib/test/test_site.py
index bcdc232c712..035913cdd05 100644
--- a/Lib/test/test_site.py
+++ b/Lib/test/test_site.py
@@ -328,13 +328,13 @@ class HelperFunctionsTests(unittest.TestCase):
             if sys.platlibdir != "lib":
                 self.assertEqual(len(dirs), 2)
                 wanted = os.path.join('xoxo', sys.platlibdir,
-                                      'python%d.%d' % sys.version_info[:2],
+                                      f'python{sysconfig._get_python_version_abi()}',
                                       'site-packages')
                 self.assertEqual(dirs[0], wanted)
             else:
                 self.assertEqual(len(dirs), 1)
             wanted = os.path.join('xoxo', 'lib',
-                                  'python%d.%d' % sys.version_info[:2],
+                                  f'python{sysconfig._get_python_version_abi()}',
                                   'site-packages')
             self.assertEqual(dirs[-1], wanted)
         else:
diff --git a/Lib/test/test_sysconfig.py b/Lib/test/test_sysconfig.py
index 9233304c6a5..37cee927686 100644
--- a/Lib/test/test_sysconfig.py
+++ b/Lib/test/test_sysconfig.py
@@ -157,7 +157,7 @@ class TestSysConfig(unittest.TestCase):
         binpath = 'bin'
         incpath = 'include'
         libpath = os.path.join('lib',
-                               'python%d.%d' % sys.version_info[:2],
+                               f'python{sysconfig._get_python_version_abi()}',
                                'site-packages')
 
         # Resolve the paths in an imaginary venv/ directory
diff --git a/Lib/test/test_venv.py b/Lib/test/test_venv.py
index 1769ed61b94..2b7d297f011 100644
--- a/Lib/test/test_venv.py
+++ b/Lib/test/test_venv.py
@@ -75,7 +75,7 @@ class BaseTest(unittest.TestCase):
             self.include = 'Include'
         else:
             self.bindir = 'bin'
-            self.lib = ('lib', 'python%d.%d' % sys.version_info[:2])
+            self.lib = ('lib', f'python{sysconfig._get_python_version_abi()}')
             self.include = 'include'
         executable = sys._base_executable
         self.exe = os.path.split(executable)[-1]
@@ -593,7 +593,8 @@ class BasicTest(BaseTest):
         libdir = os.path.join(non_installed_dir, platlibdir, self.lib[1])
         os.makedirs(libdir)
         landmark = os.path.join(libdir, "os.py")
-        stdlib_zip = "python%d%d.zip" % sys.version_info[:2]
+        abi_thread = "t" if sysconfig.get_config_var("Py_GIL_DISABLED") else ""
+        stdlib_zip = f"python{sys.version_info.major}{sys.version_info.minor}{abi_thread}"
         zip_landmark = os.path.join(non_installed_dir,
                                     platlibdir,
                                     stdlib_zip)
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 0bece8717ef..d380c422714 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -41,6 +41,7 @@ AR=		@AR@
 READELF=	@READELF@
 SOABI=		@SOABI@
 ABIFLAGS=	@ABIFLAGS@
+ABI_THREAD=	@ABI_THREAD@
 LDVERSION=	@LDVERSION@
 MODULE_LDFLAGS=@MODULE_LDFLAGS@
 GITVERSION=	@GITVERSION@
@@ -158,7 +159,7 @@ WHEEL_PKG_DIR=	@WHEEL_PKG_DIR@
 
 # Detailed destination directories
 BINLIBDEST=	@BINLIBDEST@
-LIBDEST=	$(SCRIPTDIR)/python$(VERSION)
+LIBDEST=	$(SCRIPTDIR)/python$(VERSION)$(ABI_THREAD)
 INCLUDEPY=	$(INCLUDEDIR)/python$(LDVERSION)
 CONFINCLUDEPY=	$(CONFINCLUDEDIR)/python$(LDVERSION)
 
diff --git a/Misc/NEWS.d/next/Build/2024-07-02-20-16-09.gh-issue-121103.TMef9j.rst b/Misc/NEWS.d/next/Build/2024-07-02-20-16-09.gh-issue-121103.TMef9j.rst
new file mode 100644
index 00000000000..4bc8c6de0b7
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2024-07-02-20-16-09.gh-issue-121103.TMef9j.rst
@@ -0,0 +1,3 @@
+On POSIX systems, excluding macOS framework installs, the lib directory
+for the free-threaded build now includes a "t" suffix to avoid conflicts
+with a co-located default build installation.
diff --git a/Modules/getpath.c b/Modules/getpath.c
index abed1390282..d0128b20fae 100644
--- a/Modules/getpath.c
+++ b/Modules/getpath.c
@@ -951,6 +951,11 @@ _PyConfig_InitPathConfig(PyConfig *config, int compute_path_config)
         !wchar_to_dict(dict, "executable_dir", NULL) ||
         !wchar_to_dict(dict, "py_setpath", _PyPathConfig_GetGlobalModuleSearchPath()) ||
         !funcs_to_dict(dict, config->pathconfig_warnings) ||
+#ifdef Py_GIL_DISABLED
+        !decode_to_dict(dict, "ABI_THREAD", "t") ||
+#else
+        !decode_to_dict(dict, "ABI_THREAD", "") ||
+#endif
 #ifndef MS_WINDOWS
         PyDict_SetItemString(dict, "winreg", Py_None) < 0 ||
 #endif
diff --git a/Modules/getpath.py b/Modules/getpath.py
index bc7053224aa..1f1bfcb4f64 100644
--- a/Modules/getpath.py
+++ b/Modules/getpath.py
@@ -40,6 +40,7 @@
 # EXE_SUFFIX        -- [in, opt] '.exe' on Windows/Cygwin/similar
 # VERSION_MAJOR     -- [in] sys.version_info.major
 # VERSION_MINOR     -- [in] sys.version_info.minor
+# ABI_THREAD        -- [in] either 't' for free-threaded builds or ''
 # PYWINVER          -- [in] the Windows platform-specific version (e.g. 3.8-32)
 
 # ** Values read from the environment **
@@ -172,17 +173,18 @@
 # ******************************************************************************
 
 platlibdir = config.get('platlibdir') or PLATLIBDIR
+ABI_THREAD = ABI_THREAD or ''
 
 if os_name == 'posix' or os_name == 'darwin':
     BUILDDIR_TXT = 'pybuilddir.txt'
     BUILD_LANDMARK = 'Modules/Setup.local'
     DEFAULT_PROGRAM_NAME = f'python{VERSION_MAJOR}'
-    STDLIB_SUBDIR = f'{platlibdir}/python{VERSION_MAJOR}.{VERSION_MINOR}'
+    STDLIB_SUBDIR = f'{platlibdir}/python{VERSION_MAJOR}.{VERSION_MINOR}{ABI_THREAD}'
     STDLIB_LANDMARKS = [f'{STDLIB_SUBDIR}/os.py', f'{STDLIB_SUBDIR}/os.pyc']
-    PLATSTDLIB_LANDMARK = f'{platlibdir}/python{VERSION_MAJOR}.{VERSION_MINOR}/lib-dynload'
+    PLATSTDLIB_LANDMARK = f'{platlibdir}/python{VERSION_MAJOR}.{VERSION_MINOR}{ABI_THREAD}/lib-dynload'
     BUILDSTDLIB_LANDMARKS = ['Lib/os.py']
     VENV_LANDMARK = 'pyvenv.cfg'
-    ZIP_LANDMARK = f'{platlibdir}/python{VERSION_MAJOR}{VERSION_MINOR}.zip'
+    ZIP_LANDMARK = f'{platlibdir}/python{VERSION_MAJOR}{VERSION_MINOR}{ABI_THREAD}.zip'
     DELIM = ':'
     SEP = '/'
 
diff --git a/configure b/configure
index bbfa805883c..19786f18e61 100755
--- a/configure
+++ b/configure
@@ -928,6 +928,7 @@ DEF_MAKE_RULE
 DEF_MAKE_ALL_RULE
 JIT_STENCILS_H
 REGEN_JIT_COMMAND
+ABI_THREAD
 ABIFLAGS
 LN
 MKDIR_P
@@ -8160,7 +8161,9 @@ fi
 
 # For calculating the .so ABI tag.
 
+
 ABIFLAGS=""
+ABI_THREAD=""
 
 # Check for --disable-gil
 # --disable-gil
@@ -8190,6 +8193,7 @@ printf "%s\n" "#define Py_GIL_DISABLED 1" >>confdefs.h
 
   # Add "t" for "threaded"
   ABIFLAGS="${ABIFLAGS}t"
+  ABI_THREAD="t"
 fi
 
 # Check for --with-pydebug
@@ -24738,11 +24742,11 @@ fi
 
 
 
-BINLIBDEST='$(LIBDIR)/python$(VERSION)'
+BINLIBDEST='$(LIBDIR)/python$(VERSION)$(ABI_THREAD)'
 
 
 # Check for --with-platlibdir
-# /usr/$LIDIRNAME/python$VERSION
+# /usr/$PLATLIBDIR/python$(VERSION)$(ABI_THREAD)
 
 PLATLIBDIR="lib"
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for --with-platlibdir" >&5
@@ -24761,7 +24765,7 @@ then
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 printf "%s\n" "yes" >&6; }
   PLATLIBDIR="$withval"
-  BINLIBDEST='${exec_prefix}/${PLATLIBDIR}/python$(VERSION)'
+  BINLIBDEST='${exec_prefix}/${PLATLIBDIR}/python$(VERSION)$(ABI_THREAD)'
 else
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
@@ -24775,9 +24779,9 @@ fi
 
 
 if test x$PLATFORM_TRIPLET = x; then
-  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}/config-${LDVERSION}"
+  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}${ABI_THREAD}/config-${LDVERSION}"
 else
-  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}/config-${LDVERSION}-${PLATFORM_TRIPLET}"
+  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}${ABI_THREAD}/config-${LDVERSION}-${PLATFORM_TRIPLET}"
 fi
 
 
diff --git a/configure.ac b/configure.ac
index 87c4df20818..df146cc9cf0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1739,7 +1739,9 @@ fi
 
 # For calculating the .so ABI tag.
 AC_SUBST([ABIFLAGS])
+AC_SUBST([ABI_THREAD])
 ABIFLAGS=""
+ABI_THREAD=""
 
 # Check for --disable-gil
 # --disable-gil
@@ -1756,6 +1758,7 @@ then
             [Define if you want to disable the GIL])
   # Add "t" for "threaded"
   ABIFLAGS="${ABIFLAGS}t"
+  ABI_THREAD="t"
 fi
 
 # Check for --with-pydebug
@@ -6234,11 +6237,11 @@ fi
 
 
 AC_SUBST([BINLIBDEST])
-BINLIBDEST='$(LIBDIR)/python$(VERSION)'
+BINLIBDEST='$(LIBDIR)/python$(VERSION)$(ABI_THREAD)'
 
 
 # Check for --with-platlibdir
-# /usr/$LIDIRNAME/python$VERSION
+# /usr/$PLATLIBDIR/python$(VERSION)$(ABI_THREAD)
 AC_SUBST([PLATLIBDIR])
 PLATLIBDIR="lib"
 AC_MSG_CHECKING([for --with-platlibdir])
@@ -6257,7 +6260,7 @@ if test -n "$withval" -a "$withval" != yes -a "$withval" != no
 then
   AC_MSG_RESULT([yes])
   PLATLIBDIR="$withval"
-  BINLIBDEST='${exec_prefix}/${PLATLIBDIR}/python$(VERSION)'
+  BINLIBDEST='${exec_prefix}/${PLATLIBDIR}/python$(VERSION)$(ABI_THREAD)'
 else
   AC_MSG_RESULT([no])
 fi],
@@ -6267,9 +6270,9 @@ fi],
 dnl define LIBPL after ABIFLAGS and LDVERSION is defined.
 AC_SUBST([PY_ENABLE_SHARED])
 if test x$PLATFORM_TRIPLET = x; then
-  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}/config-${LDVERSION}"
+  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}${ABI_THREAD}/config-${LDVERSION}"
 else
-  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}/config-${LDVERSION}-${PLATFORM_TRIPLET}"
+  LIBPL='$(prefix)'"/${PLATLIBDIR}/python${VERSION}${ABI_THREAD}/config-${LDVERSION}-${PLATFORM_TRIPLET}"
 fi
 AC_SUBST([LIBPL])