The philosopher Aristotle proposed long ago that a good life consists of two core elements: happiness (hedonia) and a sense of meaning (eudaimonia). What is happiness and meaning, and how do they relate to psychological wellbeing? How do these desired states or traits change across life, and can they be developed with specific interventions? What roles do self-perception and social relationships play in these phenomena? We will focus on the conceptual, methodological, and philosophical issues underlying these questions.