This book provides essential information for homeowners in California who are interested in building an accessory dwelling unit (ADU) - better known as an in-law unit. In addition, the book is useful for real estate agents and contractors who have clients who desire an ADU. The author walks the reader through his experience of building an ADU and explains how to navigate the State of California's ADU laws. The book includes helpful information on selecting the type of ADU to build, complying with local laws, choosing professionals to work on the project, designing an ADU, obtaining financing, creating a budget, and saving money. This second edition concisely explains the new California ADU laws that went into effect in 2020. In addition, the book has been updated with new information on prefabricated and manufactured ADUs, financing, public utility easements and impact fees.