The aim of the book is to model a core definition of social work. Core elements include ethical guidelines, an integral definition of the subject, theoretical frameworks, and practical methods of action. The fundamental framework is systemic thinking. Social work aims for inclusion, participation, and quality of life. Prerequisites for this are sustainable relationships, specifically: relationships on the intrapersonal level (relationship with oneself), relationships on the interpersonal level, relationships on the cultural level, relationships on the formally organized level, relationships on the network level, relationships on the societal and functional system level, relationships on the ecological level, relationships on the virtual level, and relationships on the professional assistance level. The core task of social work is to address these various relationships within the framework of the proposed concept.