Propensity score methods become increasingly popular for estimating the causal effects of an intervention. If empirical applications of this method are still unusual in education researches, examples can be found easily in other fields. However, its implementation raises several questions. The aim of this paper is to provide guidance to educational researchers regarding the estimation and the utilization of the propensity score. The various stages of its application are presented step by step: evaluation of the selection bias, construction of the propensity score and measurement of its quality, and decision on the strategies to use in the estimation of treatment effects. Methodological issues are discussed at each stage. To facilitate the understanding, an example of an experiment in kindergarten illustrates the method.