Are we in control of our own development in adulthood, or are we shaped by circumstances beyond our control? By adopting the concept of intentional self-development (ISD), this text outlines an action-theoretical approach to human development that emphasizes both an individual’s ability to shape their own development throughout the lifespan, and the extent to which this potential is limited. By examining general age-related changes and critical life events, Intentional Self-Development and Positive Ageing explores the adaptive cognitive-motivational processes that generate positive development in adulthood, including developmental tasks, cognitive changes, life-stage transitions, and biological and neural processes. Leipold goes on to discuss the concept of positive ageing, highlighting the flexibility of the term and evaluating it from multiple perspectives to demonstrate its subjectivity, as well as its importance. This text also discusses the importance of resilience in positive development, contributing to the search for conditions conducive to positive life conduct across the lifespan. This book will be essential reading for undergraduates and postgraduates studying lifespan development and gerontology, positive psychology, or health psychology, as well as researchers in those fields. It will also be of interest to developmental counsellors, clinicians, and other applied occupational groups who are seeking to understand the psychological basis of actions.