Closed-Circuit Television (CCTV) video surveillance cameras have become a popular crime control tool around the world. While the diffusion of CCTV initially occurred absent a scientific knowledge base, the technology has since become well researched. A body of literature comprising of mostly quasi-experimental evaluation studies has evolved to the point that three systematic reviews and meta-analyses have been conducted since the early 2000s. Overall findings from the research literature are highly nuanced. This chapter provides a primer on the current state of CCTV research. It discusses key considerations pertaining to CCTV research methodology and the scientific evidence on CCTV’s crime control capacity. It concludes with a discussion of important knowledge gaps and key takeaways for practitioners and policymakers.