The California Department of Transportation (Caltrans) is an executive department within the U.S. state of California. Its purpose is to improve mobility across the state.

Caltrans manages the state highway system (which includes the California Freeway and Expressway System) and is actively involved with public transportation systems throughout the state.

The department is part of the state cabinet-level California Business, Transportation and Housing Agency. Caltrans is headquartered in Sacramento.

The earliest predecessor of Caltrans was the Bureau of Highways, which was created by the California Legislature and signed into law by Governor James Budd in 1895. This agency consisted of three commissioners who were charged with analyzing the state road system and making recommendations. At the time, there was no state highway system, since roads were purely a local responsibility. The roads of California consisted of crude dirt roads maintained by county governments as well as some paved roads within city boundaries, and this ad hoc system was no longer adequate for the needs of the state's rapidly growing population. After the commissioners submitted their report to the Governor on November 25, 1896, the Legislature replaced the Bureau with the Department of Highways.