diff --git a/torax/time_step_calculator/config.py b/torax/time_step_calculator/config.py
new file mode 100644
index 00000000..d361a8ab
--- /dev/null
+++ b/torax/time_step_calculator/config.py
@@ -0,0 +1,43 @@
+# Copyright 2024 DeepMind Technologies Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Pydantic config for time step calculators."""
+
+import enum
+from torax.time_step_calculator import chi_time_step_calculator
+from torax.time_step_calculator import fixed_time_step_calculator
+from torax.time_step_calculator import time_step_calculator
+from torax.torax_pydantic import torax_pydantic
+
+
+@enum.unique
+class TimeStepCalculatorType(enum.Enum):
+  """Types of time step calculators."""
+
+  CHI = 'chi'
+  FIXED = 'fixed'
+
+
+class TimeStepCalculator(torax_pydantic.BaseModelMutable):
+  """Config for a time step calculator."""
+
+  calculator_type: TimeStepCalculatorType = TimeStepCalculatorType.CHI
+
+  @property
+  def time_step_calculator(self) -> time_step_calculator.TimeStepCalculator:
+    match self.calculator_type:
+      case TimeStepCalculatorType.CHI:
+        return chi_time_step_calculator.ChiTimeStepCalculator()
+      case TimeStepCalculatorType.FIXED:
+        return fixed_time_step_calculator.FixedTimeStepCalculator()
diff --git a/torax/torax_pydantic/model_config.py b/torax/torax_pydantic/model_config.py
new file mode 100644
index 00000000..48f70cb1
--- /dev/null
+++ b/torax/torax_pydantic/model_config.py
@@ -0,0 +1,28 @@
+# Copyright 2024 DeepMind Technologies Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Pydantic config for Torax."""
+
+from torax.time_step_calculator import config as time_step_calculator_config
+from torax.torax_pydantic import model_base
+
+
+class ToraxConfig(model_base.BaseModelMutable):
+  """Base config class for Torax.
+
+  Attributes:
+    time_step_calculator: Config for the time step calculator.
+  """
+
+  time_step_calculator: time_step_calculator_config.TimeStepCalculator
diff --git a/torax/torax_pydantic/tests/model_config_test.py b/torax/torax_pydantic/tests/model_config_test.py
new file mode 100644
index 00000000..32a94c27
--- /dev/null
+++ b/torax/torax_pydantic/tests/model_config_test.py
@@ -0,0 +1,56 @@
+# Copyright 2024 DeepMind Technologies Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unit tests for the `torax.config` module."""
+
+from absl.testing import absltest
+from absl.testing import parameterized
+from torax.config import config_loader
+from torax.torax_pydantic import model_config
+
+
+class ConfigTest(parameterized.TestCase):
+  """Unit tests for the `torax.config` module."""
+
+  def test_full_config_construction(self):
+    """Test for basic config construction."""
+
+    module = config_loader.import_module(
+        ".tests.test_data.test_iterhybrid_newton",
+        config_package="torax",
+    )
+
+    # Test only the subset of config fields that are currently supported.
+    module_config = {
+        key: module.CONFIG[key]
+        for key in model_config.ToraxConfig.model_fields.keys()
+    }
+    config_pydantic = model_config.ToraxConfig.from_dict(module_config)
+
+    self.assertEqual(
+        config_pydantic.time_step_calculator.calculator_type.value,
+        module_config["time_step_calculator"]["calculator_type"],
+    )
+
+    # The full model should always be serializable.
+    with self.subTest("json_serialization"):
+      config_json = config_pydantic.model_dump_json()
+      config_pydantic_roundtrip = model_config.ToraxConfig.model_validate_json(
+          config_json
+      )
+      self.assertEqual(config_pydantic, config_pydantic_roundtrip)
+
+
+if __name__ == "__main__":
+  absltest.main()