This study examines the comparative effectiveness of using law enforcement agencies for child protective investigation (CPI), in contrast with the traditional approach of CPI conducted by the public child welfare agency. The analysis uses 2006-2007 data from a natural experiment conducted in Florida to show modest differences in performance and cost-efficiency between the two approaches to CPI. These findings may have implications for other states considering outsourcing CPI to law enforcement. (Contains 5 tables and 2 figures.)