Evaluation systems emerged years ago in the business field within the private sector. Today, the public sector is also faced with the need to apply these systems to achieve higher levels of effectiveness and efficiency in the management and application of increasingly restricted financial resources so as not to incur high levels of public deficit. To this should be added the growing demand for information from citizens, who demand a greater capacity for control over those who have the responsibility to govern and manage public money. The reasons that determine the distribution of these resources, as well as the success or failure of the different interventions that are put in place, must be explained and justified. The evaluation must provide such information in an exercise of transparency (accountability) and governance.   Initially, the evaluation focused on the mechanisms for programming, implementation and execution of projects and programs, with little attention being paid to the impact of public actions financed from the State budgets. However, in recent years, great efforts have been made by some international organizations (World Bank, Economic Commission for Latin America and the Caribbean, European Commission ...) to promote impact evaluations of public interventions; in other words, establish a causal link between the public policy that is evaluated and the effects observed by the evaluator. Currently, this type of evaluation has acquired a relevant role in the design of programs and public policies and has become the standard approach to identify its effects.  The objective of this article is to highlight the advantages and disadvantages of the evaluation of public policies, as well as the main issues to be resolved in this process.