According to experts impact evaluation is the way to prove the value that training brings to the organizations and its members (productivity). However, due to the methodological difficulties in its implementation, it is not a standard practice in training programs. This paper analyzes the reason of lack of generalization of these techniques as well as the methodological, structural and pedagogic conditions that support their implementation. The supporting data for this paper is based on research work done in the Argentina, Chile and Colombia, public and private sector, which focuses on a comparative analysis of impact evaluation in programs of human resources training. From these conclusions, certain models of impact evaluation, which work in practice, are described