Social competences are assessed for a number of reasons. Such assessments may be based on various approaches, such as the examination of actions in social settings or the utilization of the individual's self-reflection abilities. Following that, it needs to be clarified, when evidence on social competences is considered valid. This raises the question of validation strategies for approaches to competence assessment. Hence, this article addresses assessments of social competences on two levels: on the level of assessment approaches resp. tools and on the level of requirements for the validation of evidence. The aim is to sketch out variations of assessment tools and exemplify this with regard to two complementary research and design projects.