Areas of developmental knowledge directly applied to child and youth care work are: (1) attachment formation and "beginnings" early or later in life; (2) rhythmicity as the underpinning for the mutuality of personal interactions; (3) transitional objects and how they are utilized in facing new life situations; (4) trial-and-error learning as a fundamental learning mode; and (5) personal value acquisition. A developmental perspective is advocated because it deals with the very questions that engage child and youth care workers in their daily work and is suitable because of its rich resources of immediately applicable knowledge and empirically verifiable research. 3 notes, 27 references. (Author abstract modified)