diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index 3457a81f90..8274d6369e 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -45,7 +45,7 @@ jobs:
 
       - name: Run Tox (CPython)
         if: "${{ !startsWith(matrix.py, 'pypy') }}"
-        run: tox -e static,optimized,py3
+        run: tox -e static,py3_eest,optimized,py3
 
       - name: Run Tox (PyPy)
         if: "${{ startsWith(matrix.py, 'pypy') }}"
diff --git a/.gitignore b/.gitignore
index 144dc04c86..fd08eaf32b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -58,3 +58,5 @@ pip-delete-this-directory.txt
 tests/execution-spec-generated-tests
 tests/fixtures
 tests/t8n_testdata
+
+fixtures
diff --git a/.gitmodules b/.gitmodules
index e69de29bb2..4e4c40f501 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "eest_tests/execution-spec-tests"]
+	path = eest_tests/execution-spec-tests
+	url = https://github.com/ethereum/execution-spec-tests.git
diff --git a/eest_tests/conftest.py b/eest_tests/conftest.py
new file mode 100644
index 0000000000..190ce053af
--- /dev/null
+++ b/eest_tests/conftest.py
@@ -0,0 +1,8 @@
+import pytest
+from ethereum_spec_tools.evm_tools.t8n.transition_tool import EELST8N
+from ethereum_clis import TransitionTool
+
+
+@pytest.hookimpl(tryfirst=True)
+def pytest_configure(config):
+    TransitionTool.set_default_tool(EELST8N)
diff --git a/eest_tests/execution-spec-tests b/eest_tests/execution-spec-tests
new file mode 160000
index 0000000000..6cf5107cee
--- /dev/null
+++ b/eest_tests/execution-spec-tests
@@ -0,0 +1 @@
+Subproject commit 6cf5107cee0eae1c2d4dd6a5ef5bc729aea6c379
diff --git a/pyproject.toml b/pyproject.toml
index 7ea422b829..0d5cac2270 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -26,6 +26,8 @@ dependencies = [
     "ethereum-types>=0.2.1,<0.3",
     "ethereum-rlp>=0.1.4,<0.2",
     "cryptography>=45.0.1,<46",
+    "ethereum-execution-spec-tests @ git+https://github.com/ethereum/execution-spec-tests@6cf5107cee0eae1c2d4dd6a5ef5bc729aea6c379",
+    "ethereum-spec-evm-resolver @ git+https://github.com/petertdavies/ethereum-spec-evm-resolver",
 ]
 
 [tool.setuptools]
@@ -152,11 +154,11 @@ packages = [
 
 [project.optional-dependencies]
 test = [
-    "pytest>=7.4.0,<8",
+    "pytest>=8,<9",
     "pytest-cov>=4.1.0,<5",
     "pytest-xdist>=3.3.1,<4",
     "GitPython>=3.1.0,<3.2",
-    "filelock>=3.12.3,<3.13",
+    "filelock>=3.15.1,<4",
     "requests",
     "requests-cache>=1.2.1,<2",
 ]
@@ -195,6 +197,7 @@ ethereum-spec-sync = "ethereum_spec_tools.sync:main"
 ethereum-spec-new-fork = "ethereum_spec_tools.new_fork:main"
 ethereum-spec-patch = "ethereum_spec_tools.patch_tool:main"
 ethereum-spec-evm = "ethereum_spec_tools.evm_tools:main"
+ethereum-spec-fill = "cli.pytest_commands.fill:fill"
 
 [project.entry-points."docc.plugins"]
 "ethereum_spec_tools.docc.discover" = "ethereum_spec_tools.docc:EthereumDiscover"
diff --git a/src/ethereum_spec_tools/evm_tools/t8n/transition_tool.py b/src/ethereum_spec_tools/evm_tools/t8n/transition_tool.py
new file mode 100644
index 0000000000..c84503cfb0
--- /dev/null
+++ b/src/ethereum_spec_tools/evm_tools/t8n/transition_tool.py
@@ -0,0 +1,128 @@
+"""
+Implementation of the EELS T8N for execution-spec-tests.
+"""
+
+import json
+import tempfile
+from io import StringIO
+from typing import Any, Dict, Optional
+
+from ethereum_clis.clis.execution_specs import ExecutionSpecsExceptionMapper
+from ethereum_clis.file_utils import dump_files_to_directory
+from ethereum_clis.transition_tool import TransitionTool, model_dump_config
+from ethereum_clis.types import TransitionToolOutput
+from ethereum_test_forks import Fork
+
+import ethereum
+
+from .. import create_parser
+from ..utils import get_supported_forks
+from . import T8N
+
+
+class EELST8N(TransitionTool):
+    """Implementation of the EELS T8N for execution-spec-tests."""
+
+    def __init__(
+        self,
+        *,
+        trace: bool = False,
+    ):
+        """Initialize the EELS Transition Tool interface."""
+        self.exception_mapper = ExecutionSpecsExceptionMapper()
+        self.trace = trace
+        self._info_metadata: Optional[Dict[str, Any]] = {}
+
+    def version(self) -> str:
+        """Version of the t8n tool."""
+        return ethereum.__version__
+
+    def is_fork_supported(self, fork: Fork) -> bool:
+        """Return True if the fork is supported by the tool."""
+        return fork.transition_tool_name() in get_supported_forks()
+
+    def evaluate(
+        self,
+        *,
+        transition_tool_data: TransitionTool.TransitionToolData,
+        debug_output_path: str = "",
+        slow_request: bool = False,  # noqa: U100, F841
+    ) -> TransitionToolOutput:
+        """
+        Evaluate using the EELS T8N entry point.
+        """
+        request_data = transition_tool_data.get_request_data()
+        request_data_json = request_data.model_dump(
+            mode="json", **model_dump_config
+        )
+
+        t8n_args = [
+            "t8n",
+            "--input.alloc=stdin",
+            "--input.env=stdin",
+            "--input.txs=stdin",
+            "--output.result=stdout",
+            "--output.body=stdout",
+            "--output.alloc=stdout",
+            f"--state.fork={request_data_json['state']['fork']}",
+            f"--state.chainid={request_data_json['state']['chainid']}",
+            f"--state.reward={request_data_json['state']['reward']}",
+        ]
+
+        if transition_tool_data.state_test:
+            t8n_args.append("--state-test")
+
+        temp_dir = tempfile.TemporaryDirectory()
+        if self.trace:
+            t8n_args.extend(
+                [
+                    "--trace",
+                    "--trace.memory",
+                    "--trace.returndata",
+                    f"--output.basedir={temp_dir.name}",
+                ]
+            )
+
+        parser = create_parser()
+        t8n_options = parser.parse_args(t8n_args)
+
+        out_stream = StringIO()
+
+        in_stream = StringIO(json.dumps(request_data_json["input"]))
+
+        t8n = T8N(t8n_options, out_stream, in_stream)
+        t8n.run()
+
+        output_dict = json.loads(out_stream.getvalue())
+        output: TransitionToolOutput = TransitionToolOutput.model_validate(
+            output_dict, context={"exception_mapper": self.exception_mapper}
+        )
+
+        if debug_output_path:
+            dump_files_to_directory(
+                debug_output_path,
+                {
+                    "input/alloc.json": request_data.input.alloc,
+                    "input/env.json": request_data.input.env,
+                    "input/txs.json": [
+                        tx.model_dump(mode="json", **model_dump_config)
+                        for tx in request_data.input.txs
+                    ],
+                },
+            )
+
+            dump_files_to_directory(
+                debug_output_path,
+                {
+                    "output/alloc.json": output.alloc,
+                    "output/result.json": output.result,
+                },
+            )
+
+        if self.trace:
+            self.collect_traces(
+                output.result.receipts, temp_dir, debug_output_path
+            )
+        temp_dir.cleanup()
+
+        return output
diff --git a/tox.ini b/tox.ini
index 3724650694..8ae7dd2a26 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 min_version = 2.0
-envlist = py3,pypy3,static
+envlist = py3,pypy3,py3_eest,static
 
 [testenv:static]
 extras =
@@ -30,7 +30,26 @@ commands =
         --no-cov-on-fail \
         --cov-branch \
         --ignore-glob='tests/fixtures/*' \
-        --basetemp="{temp_dir}/pytest"
+        --basetemp="{temp_dir}/pytest" \
+        tests
+
+[testenv:py3_eest]
+extras =
+    test
+commands =
+    fill \
+        -m "not slow and not zkevm and not benchmark" \
+        -n auto --maxprocesses 6 \
+        --basetemp="{temp_dir}/pytest" \
+        --clean \
+        eest_tests/execution-spec-tests/tests
+    fill \
+        -m "not slow and not zkevm and not benchmark" \
+        -n auto --maxprocesses 6 \
+        --basetemp="{temp_dir}/pytest" \
+        --clean \
+        --fork Osaka \
+        eest_tests/execution-spec-tests/tests/osaka
 
 [testenv:pypy3]
 extras =
@@ -38,14 +57,25 @@ extras =
 passenv =
     PYPY_GC_MAX
 commands =
-    pytest \
+    fill \
         --tb=no \
         --show-capture=no \
         --disable-warnings \
-        -m "not slow" \
-        -n auto --maxprocesses 5 \
-        --ignore-glob='tests/fixtures/*' \
-        --basetemp="{temp_dir}/pytest"
+        -m "not slow and not zkevm and not benchmark" \
+        -n auto --maxprocesses 3 \
+        --basetemp="{temp_dir}/pytest" \
+        --clean \
+        eest_tests/execution-spec-tests/tests
+    fill \
+        --tb=no \
+        --show-capture=no \
+        --disable-warnings \
+        -m "not slow and not zkevm and not benchmark" \
+        -n auto --maxprocesses 3 \
+        --basetemp="{temp_dir}/pytest" \
+        --clean \
+        --fork Osaka \
+        eest_tests/execution-spec-tests/tests/osaka
 
 [testenv:optimized]
 extras =
@@ -60,7 +90,8 @@ commands =
         --ignore-glob='tests/fixtures/*' \
         --ignore-glob='tests/test_t8n.py' \
         --basetemp="{temp_dir}/pytest" \
-        --optimized
+        --optimized \
+        tests
 
 [testenv:doc]
 basepython = python3
diff --git a/vulture_whitelist.py b/vulture_whitelist.py
index 8c0cc7c08c..ae8bcbe564 100644
--- a/vulture_whitelist.py
+++ b/vulture_whitelist.py
@@ -10,6 +10,7 @@
 )
 from ethereum_spec_tools.evm_tools.t8n.env import Ommer
 from ethereum_spec_tools.evm_tools.t8n.evm_trace import Trace, FinalTrace
+from ethereum_spec_tools.evm_tools.t8n.transition_tool import EELST8N
 from ethereum_spec_tools.lint.lints.glacier_forks_hygiene import (
     GlacierForksHygiene,
 )
@@ -54,6 +55,13 @@
 _EvmToolHandler.do_POST
 _EvmToolHandler.log_request
 
+# src/ethereum_spec_tools/evm_tools/transition_tool.py
+EELST8N
+EELST8N._info_metadata
+EELST8N.version
+EELST8N.is_fork_supported
+EELST8N.evaluate
+
 # src/ethereum_spec_tools/loaders/fixture_loader.py
 Load._network
 
diff --git a/whitelist.txt b/whitelist.txt
index 62cef423cc..7edf451b1b 100644
--- a/whitelist.txt
+++ b/whitelist.txt
@@ -494,4 +494,7 @@ SECP256R1P
 secp256r1
 sig
 
-CLZ
\ No newline at end of file
+CLZ
+EELST8N
+clis
+T8
\ No newline at end of file