This book is written for both teaching and practice. Based on the premise that a proper psychological assessment is primarily characterized by its comprehensibility, it provides clear guidelines on how this can be achieved. Starting from the research question and the cover sheet, it addresses requirements and hypotheses, the selection of diagnostic methods, the diagnostic interview, the presentation of results in relation to different classes of procedures, opinions, decisions, and finally recommendations (interventions). Standardized result presentations are proposed for various types of psychological diagnostic procedures. For each individual step, the theoretical background is discussed along with fundamental aspects and considerations that need to be taken into account, and translated into practical instructions. Numerous examples are provided.