This chapter focuses on three areas that exemplify the range and scope of both theory and practice in contemporary forensic psychology – psychology in the courtroom, advances in theories of criminal behaviour, and impact of these theories on crime prevention strategies. Many forensic psychology practitioners will appear in the courtroom. Any field of applied psychology is bound to meet its critics who dismiss its theories, its methods, its appreciation of real world issues, and the generalizability of the evidence it produces. The search for an explanation for criminal behaviour has a long history, with distinguished contributions from many disciplines including psychology. The emergence of a social learning approach to the explanation of criminal behaviour can be traced to a line of theorizing, beginning with E. H. Sutherland’s differential association theory, that emphasized the importance of learning in understanding criminal behaviour.