Logics, politics and practices for service quality assessment have been settling down on the Third Sector associations of socio-educational action. This type of organizational pathways are similar to those procedures carried out during the recent years in other educational contexts, which have significantly diminished the real and effective participation of the main agents involved. This is added to the lack of standards for evaluating perceived associative participation. In view of this problem, we aimed to establish valid indicators that allow registering the perspective of the partners and professionals about their associative participation. To analyze these standards, it has been previously defined one construct on perceived associative participation, based on the results of previous research and the theoretical foundations derived from different areas of knowledge; mainly, educational psychology and sociology. The theoretical construct has been dimensioned in four parts -information, services, involvement and associationism- and submitted to the judgment of 17 experts from universities and 15 from the Third Sector. The experts were given three Likert-style scales to measure their degree of agreement with the construct related to three evaluation criterion: pertinence, importance and expiration of each component, in each of the four dimensions. Given the sample size and distribution of the points, it has been computed non-parametric tests to obtain the internal consistency of the agreement and the degree of agreement between the subjects. Eventually, the experts agreed that the contents of this construct have great pertinence, importance and stability. In this sense, the agreed structure offers a valid content for designing instruments of different nature, as well as for evaluating strategies for socio-educational practice.