Wild tigers are in a critical state with an estimated population decline of more than 95% over the past century. Improving the capacity and effectiveness of law enforcement in reducing poaching of tigers is an immediate priority to secure remaining wild populations in source sites. From 2008–2010, standardized patrol-based law enforcement monitoring (LEM) was established under the Tigers Forever Program across 8 key tiger sites in order to improve and evaluate law enforcement interventions. Patrol-based monitoring has the distinct advantage of providing regular and rapid information on illegal activities and ranger performance, although, until recently, it has received relatively little scrutiny from the conservation community. The present paper outlines a framework for implementation of LEM in tiger source sites using MIST, a computerized management information system for ranger-based data collection. The framework addresses many of the technical, practical and institutional challenges involved in the design, implementation, sustainability and evaluation of LEM. Adoption of such a framework for LEM is a cost-effective strategy to improve the efficiency of law enforcement efforts, to increase the motivation of enforcement staff and to promote the accountability of law enforcement agencies in addressing threats to tigers. When combined with independent, systematic and science-based monitoring of tigers and their prey, LEM has great potential for evaluating the effectiveness of protection-based conservation investments.