Abstract: The opportunity approach to compliance focuses on understanding how rule-breaking behaviour takes place and then tries to reduce the factors that enable rule breaking. This chapter reviews two core criminological theories within the opportunity approach: routine activity theory and situational crime prevention. The chapter assesses empirical evidence as to whether policies based on these theories can reduce rule-violating behaviour. Moreover, it discusses the extent to which the opportunity approach can result in displacement and adaptation effects. And, finally, it explores potential downsides to the opportunity approach such as victim blaming and reductions in autonomy and freedom of choice.