Summary Ascertaining the effectiveness of a motivational training is considered one of the most difficult functions of evaluation research since one must account for numerous biases that can distort the results. When conducting an evaluation of a complex training - not just a single measurement - one is confronted with the problem that the evaluation is executing a simultaneous test of an entire family of theories. These embrace (1) the motivational theory that underlies the conception of the motivational training, (2) the promotional goals that are derived from these theories, and (3) the practical implementation of a training that aims to attain these promotional goals. A further problem is the asymmetry inherent in the findings of evaluations that can either attest to or cast doubt over the success of a training. In the first case, one runs the risk of overgeneralizing positive results; in the second, one is faced with the difficulty of determining the precise source of these negative results, which can be anchored on one of three different levels. This article offers, from a metatheoretical perspective, a few preliminary responses to the problems associated with the evaluation of complex motivational trainings.