Many surgeries are performed in freestanding, or “same-day,” ambulatory surgery centers (ASCs), whose numbers have increased dramatically over the past 11 years. However, due to a legal decision that removed reporting requirements for ASCs in the state, little is known about the volume of procedures, type of procedures, and financial operation of the vast majority of these facilities. This report looks at the most recent data on the supply, use, quality, and finances of freestanding ASCs in California.