This chapter continues to explore the co-construction of the narrative social work interview, emphasizing the differential use of developmental theory as a means of comprehending clients’ life span transitions. The theoretical content about developmental processes discussed includes Carel Germain and Alex Gitterman’s (2008) life model, which focuses on transitions as person–environment concepts; Erik Erikson’s fifth stage of the healthy personality, which addresses identity formation in adolescence; and Terry Cross’s (2003) relational self-construct, which concentrates on development as a collective interactional process. Urie Bronfenbrenner’s (1979) chronosystem, which highlights sociohistorical events, and Ludwig von Bertalanffy’s general systems approach, which concentrates on people’s response to systemic stress are also explored. These theoretical concepts are critiqued to better understand how they can be tailored to assess each client’s situation. Practice examples involving adolescents with differing developmental trajectories who are exploring their personal identity illustrate the synthesis and differential application of concepts related to resilient social functioning across the four practice phases of the resilience-enhancing stress model.