diff --git a/.claude/scripts/setup-env.sh b/.claude/scripts/setup-env.sh
index f5d28a3f1..f6a1e8366 100755
--- a/.claude/scripts/setup-env.sh
+++ b/.claude/scripts/setup-env.sh
@@ -16,7 +16,7 @@ if [ "$(printf '%s\n' "3.13" "$CURRENT_PY" | sort -V | head -1)" != "3.13" ]; th
     echo "Upgrading python3 default to 3.13..."
     # Find best available Python >= 3.13
     TARGET=""
-    for ver in python3.14 python3.13; do
+    for ver in python3.15 python3.14 python3.13; do
         if command -v "$ver" &>/dev/null; then
             TARGET=$(command -v "$ver")
             break
@@ -40,8 +40,8 @@ fi
 
 # 2. Clone CPython source if not present (needed for scripts/update_lib)
 if [ ! -d "cpython" ]; then
-    echo "Cloning CPython v3.14.3 (shallow)..."
-    git clone --depth 1 --branch v3.14.3 https://github.com/python/cpython.git cpython
+    echo "Cloning CPython v3.15.0 (shallow)..."
+    git clone --depth 1 --branch v3.15.0 https://github.com/python/cpython.git cpython
     echo "CPython source ready."
 else
     echo "CPython source already present."
diff --git a/.github/workflows/pyperformance.yaml b/.github/workflows/pyperformance.yaml
index 1d304582c..d6ef2764b 100644
--- a/.github/workflows/pyperformance.yaml
+++ b/.github/workflows/pyperformance.yaml
@@ -63,7 +63,7 @@ jobs:
       - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         id: cpython
         with:
-          python-version: "3.14"
+          python-version: "3.15"
 
       - name: Restore cache
         uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
diff --git a/.github/workflows/update-doc-db.yml b/.github/workflows/update-doc-db.yml
index 8874c3aea..3abdf27de 100644
--- a/.github/workflows/update-doc-db.yml
+++ b/.github/workflows/update-doc-db.yml
@@ -8,7 +8,7 @@ on:
       python-version:
         description: Target python version to generate doc db for
         type: string
-        default: "3.14.7"
+        default: "3.15.0"
       base-ref:
         description: Base branch to create the update branch from
         type: string
diff --git a/.github/workflows/upgrade-pylib.lock.yml b/.github/workflows/upgrade-pylib.lock.yml
index c08d19058..0199a8850 100644
--- a/.github/workflows/upgrade-pylib.lock.yml
+++ b/.github/workflows/upgrade-pylib.lock.yml
@@ -24,7 +24,7 @@
 # Pick an out-of-sync Python library from the todo list and upgrade it
 # by running `scripts/update_lib quick`, then open a pull request.
 #
-# frontmatter-hash: 3129480d6628afe028911bb8b31b6bb3b5eb251e395f00ed0677922cd21727cb
+# frontmatter-hash: 4c8478ae37e731fb9e34ca116a5fcbdd4f23b00f6f4d148df40f4db52b3bea6e
 
 name: "Upgrade Python Library"
 "on":
@@ -44,7 +44,7 @@ run-name: "Upgrade Python Library"
 
 env:
   ISSUE_ID: "6839"
-  PYTHON_VERSION: v3.14.3
+  PYTHON_VERSION: v3.15.0
 
 # Cache configuration from frontmatter was processed and added to the main job steps
 
@@ -109,7 +109,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         with:
-          python-version: '3.14'
+          python-version: '3.15'
       - name: Create gh-aw temp directory
         run: bash /opt/gh-aw/actions/create_gh_aw_tmp_dir.sh
       # Cache configuration from frontmatter processed below
diff --git a/.github/workflows/upgrade-pylib.md b/.github/workflows/upgrade-pylib.md
index cd05eb777..fbb7087a4 100644
--- a/.github/workflows/upgrade-pylib.md
+++ b/.github/workflows/upgrade-pylib.md
@@ -28,7 +28,7 @@ engine: copilot
 
 runtimes:
   python:
-    version: "3.14"
+    version: "3.15"
 
 tools:
   bash:
@@ -52,7 +52,7 @@ cache:
     - cpython-lib-
 
 env:
-  PYTHON_VERSION: "v3.14.7"
+  PYTHON_VERSION: "v3.15.0"
   ISSUE_ID: "6839"
 ---
 
diff --git a/.python-version b/.python-version
index a128d5c0d..f02113fe8 100644
--- a/.python-version
+++ b/.python-version
@@ -1 +1 @@
-3.14.7
+3.15.0
diff --git a/AGENTS.md b/AGENTS.md
index ae24d4167..9aa4cc677 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -4,7 +4,7 @@ This document provides guidelines for AI coding agents (GitHub Copilot, Claude C
 
 ## Project Overview
 
-RustPython is a Python 3 interpreter written in Rust, implementing Python 3.14.0+ compatibility. The project aims to provide:
+RustPython is a Python 3 interpreter written in Rust, targeting Python 3.15 with compatibility work in progress. The project aims to provide:
 
 - A complete Python-3 environment entirely in Rust (not CPython bindings)
 - A clean implementation without compatibility hacks
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 637ecf099..710bb2caf 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -49,7 +49,7 @@ RustPython requires the following:
       stable version: `rustup update stable`
     - If you do not have Rust installed, use [rustup](https://rustup.rs/) to
       do so.
-- CPython version 3.14 or higher
+- CPython version 3.15 or higher
     - CPython can be installed by your operating system's package manager,
       from the [Python website](https://www.python.org/downloads/), or
       using a third-party distribution, such as 
diff --git a/README.md b/README.md
index 1fc891b79..c28e2fbed 100644
--- a/README.md
+++ b/README.md
@@ -2,9 +2,11 @@
 
 # [RustPython](https://rustpython.github.io/)
 
-A Python-3 (CPython >= 3.14.0) Interpreter written in Rust :snake: :scream:
+A Python-3 interpreter written in Rust, targeting CPython 3.15 :snake: :scream:
 :metal:.
 
+Python 3.15 compatibility is a work in progress.
+
 [![Build Status](https://github.com/RustPython/RustPython/workflows/CI/badge.svg)](https://github.com/RustPython/RustPython/actions?query=workflow%3ACI)
 [![codecov](https://codecov.io/gh/RustPython/RustPython/branch/main/graph/badge.svg)](https://codecov.io/gh/RustPython/RustPython)
 [![CodSpeed](https://img.shields.io/endpoint?url=https://codspeed.io/badge.json)](https://app.codspeed.io/RustPython/RustPython?utm_source=badge)
diff --git a/crates/vm/build.rs b/crates/vm/build.rs
index 867cf5775..098cf05aa 100644
--- a/crates/vm/build.rs
+++ b/crates/vm/build.rs
@@ -22,8 +22,8 @@ fn main() {
     }
     println!("cargo:rerun-if-changed=../../Lib/importlib/_bootstrap.py");
 
-    // = 3.14.0alpha
-    python_version(3, 14, 0, "alpha", 0);
+    // = 3.15.0alpha
+    python_version(3, 15, 0, "alpha", 0);
 
     println!("cargo:rustc-env=RUSTPYTHON_GIT_HASH={}", git_hash());
     println!(
diff --git a/crates/vm/src/stdlib/_ast.rs b/crates/vm/src/stdlib/_ast.rs
index 497dec48b..6560d7ee1 100644
--- a/crates/vm/src/stdlib/_ast.rs
+++ b/crates/vm/src/stdlib/_ast.rs
@@ -1804,7 +1804,7 @@ pub(crate) fn parse<E: From<CompileError>>(
 ) -> Result<PyObjectRef, E> {
     let source_file = SourceFileBuilder::new(filename.to_owned(), source.to_owned()).finish();
     let mut options = parser::ParseOptions::from(mode);
-    let target_version = target_version.unwrap_or(ast::PythonVersion::PY314);
+    let target_version = target_version.unwrap_or(ast::PythonVersion::PY315);
     if let Some(error) = feature_version_syntax_error(source, &source_file, target_version) {
         return Err(error.into());
     }
@@ -2045,7 +2045,7 @@ pub(crate) fn parse_func_type<E: From<CompileError>>(
     let parse_expr = |expr_src: &str| -> Result<ast::Expr, CompileError> {
         let source_file = SourceFileBuilder::new(filename.to_owned(), expr_src.to_owned()).finish();
         let options = parser::ParseOptions::from(parser::Mode::Expression)
-            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY314));
+            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY315));
         let parsed = parser::parse(expr_src, options).map_err(|parse_error| {
             let range = text_range_to_source_range(&source_file, parse_error.location);
             CompileError::from(ParseError {
@@ -2080,7 +2080,7 @@ pub(crate) fn parse_func_type<E: From<CompileError>>(
         let call_source = format!("{ARG_PREFIX}{inner})");
         let source_file = SourceFileBuilder::new(filename.to_owned(), call_source.clone()).finish();
         let options = parser::ParseOptions::from(parser::Mode::Expression)
-            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY314));
+            .with_target_version(target_version.unwrap_or(ast::PythonVersion::PY315));
         let parsed = parser::parse(&call_source, options).map_err(|parse_error| {
             let range = text_range_to_source_range(&source_file, parse_error.location);
             CompileError::from(ParseError {
diff --git a/crates/vm/src/vm/mod.rs b/crates/vm/src/vm/mod.rs
index 238b19a2b..ac1b96a46 100644
--- a/crates/vm/src/vm/mod.rs
+++ b/crates/vm/src/vm/mod.rs
@@ -1607,7 +1607,7 @@ impl VirtualMachine {
     /// ```no_run
     /// use rustpython_vm::Interpreter;
     /// Interpreter::without_stdlib(Default::default()).enter(|vm| {
-    ///     let bytes = std::fs::read("__pycache__/<input>.rustpython-314.pyc").unwrap();
+    ///     let bytes = std::fs::read("__pycache__/<input>.rustpython-315.pyc").unwrap();
     ///     let main_scope = vm.new_scope_with_main().unwrap();
     ///     vm.run_pyc_bytes(&bytes, main_scope);
     /// });
diff --git a/extra_tests/snippets/stdlib_sys.py b/extra_tests/snippets/stdlib_sys.py
index 9dba301fb..7d8dc0e33 100644
--- a/extra_tests/snippets/stdlib_sys.py
+++ b/extra_tests/snippets/stdlib_sys.py
@@ -25,6 +25,12 @@ assert "sys" in sys.builtin_module_names
 assert isinstance(sys.implementation.name, str)
 assert isinstance(sys.implementation.cache_tag, str)
 
+if sys.implementation.name == "rustpython":
+    assert sys.version_info == (3, 15, 0, "alpha", 0)
+    assert sys.hexversion == 0x030F00A0
+    assert sys.version.startswith("3.15.0.alpha (")
+    assert sys.implementation.cache_tag == "rustpython-315"
+
 assert sys.getfilesystemencoding() == "utf-8"
 assert sys.getfilesystemencodeerrors().startswith("surrogate")
 
diff --git a/scripts/libc_posix.py b/scripts/libc_posix.py
index 82f3eb96d..139235244 100644
--- a/scripts/libc_posix.py
+++ b/scripts/libc_posix.py
@@ -8,7 +8,7 @@ import urllib.request
 
 import tomllib
 
-CPYTHON_VERSION = "3.14"
+CPYTHON_VERSION = "3.15"
 
 CONSTS_PATTERN = re.compile(r"\b_*[A-Z]+(?:_+[A-Z]+)*_*\b")
 
diff --git a/scripts/whats_left.py b/scripts/whats_left.py
index 40b7b5be9..9adae4c9c 100755
--- a/scripts/whats_left.py
+++ b/scripts/whats_left.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env -S python3 -I
 # /// script
-# requires-python = ">=3.14"
+# requires-python = ">=3.15.0"
 # ///
 
 # This script generates Lib/snippets/whats_left_data.py with these variables defined:
@@ -39,9 +39,9 @@ GENERATED_FILE = "extra_tests/not_impl.py"
 implementation = platform.python_implementation()
 if implementation != "CPython":
     sys.exit(f"whats_left.py must be run under CPython, got {implementation} instead")
-if sys.version_info[:2] < (3, 14):
+if sys.version_info[:2] < (3, 15):
     sys.exit(
-        f"whats_left.py must be run under CPython 3.14 or newer, got {implementation} {sys.version} instead. If you have uv, try `uv run python -I scripts/whats_left.py` to select a proper Python interpreter easier."
+        f"whats_left.py must be run under CPython 3.15 or newer, got {implementation} {sys.version} instead. If you have uv, try `uv run python -I scripts/whats_left.py` to select a proper Python interpreter easier."
     )