Many of the outcomes of environmental plans are difficult to measure. Therefore, little is known as to whether such plans achieve their goals, whether outcomes are reached and lessons learned to influence future plans. Our study aims to address this gap by systematically evaluating the implementation of Local Environmental Action Plans (LEAPs) of 29 counties in Romania and the factors affecting it. We draw on both quantitative (official statistical data) and qualitative (planners’ assessments) evaluation methods and two conceptions of plan implementation success (conformance and performance based) to assess LEAP implementation. Our findings indicate mixed levels of conformance and performance. While the implementation of LEAPs conforms with the plans from the perspective of progress of overall policy implementation, this does not conform with the plans in terms of positive changes on the ground. LEAPs perform well in mitigating local environmental problems and coordinating with other planning initiatives but badly in terms of their usefulness in the decision-making process, having little influence on lower-level plans. Furthermore, the quality of LEAPs may not be important in relation to their implementation, while investments in the capacity of planning agencies, as well as local political support and participatory approaches, may improve the implementation of LEAPs in the future. The results of our study may assist the devising bodies in enhancing the implementation of future versions of LEAPs by revealing the main opportunities and constraints influencing implementation.