Abstract
How can we account for the variance in the level of implementation of and compliance with international agreements? Noting that answers to this question have been sought by pursuing at least three different paths of research, the author outlines three basic models and briefly discusses some of the main propositions and policy implications that can be derived from these models. The first model explicates the calculations that a unitary rational actor would perform in deciding whether or not to honour its commitments. The second examines the domestic politics of implementation, while the third focuses on the ideational basis of compliance, highlighting processes of learning and policy diffusion.