Social work practice takes place between persons in families and other social institutions, such as schools, health systems, welfare systems or courts. Drawing from multi-disciplinary theoretical sources, the article brings together social work and family therapy to develop a contemporary model of social work practice with families. There are five generic principles of family systemic practice: 1) persons are inherently relational; 2) families have resilient strengths; 3) family life cycles proceed systemically generating relational tasks for family members; 4) repetitive family interaction generates relational structures; 5) cultures, as perceived by family members, are themselves in dynamic motion, necessitating a transcultural understanding of family interaction.