Current research focuses on competence development and complex professional tasks. However, "learning processes" towards the integration of knowledge, skills and attitudes largely remain a black box. This article conceptualises three integration processes, in analogy to theories on transfer. Knowledge, skills and attitudes are defined, reconciling different research perspectives. Low-road integration is hypothesised to occur through practice towards automatisation. High-road integration requires reflection on the task besides practice. Transformative integration requires critical (self)reflection and openness to change. A model of different professional tasks is presented, offering hypotheses regarding different integration processes, which provides a basis for further empirical research. (Contains 2 tables and 1 figure.)