Whether happiness can change might seem like an odd question to ask. Of course! I felt really good after the pizza last night, and when I missed the bus this morning I felt terrible. But wait, now that I think about it, this week has actually been pretty much the same as last week, so I guess my happiness does not change. Although … come to think of it … I might actually be in a rut … I really should do something about the slow decline of my life satisfaction. These are the dimensions of happiness that Stability of Happiness explores, and it does an excellent job. This book is perhaps the definitive text on the status of research into affective states and their dynamics. It makes a nice complement to the seminal Well-Being: The Foundations of Hedonic Psychology. The two books, taken together, are an ideal starting point for anyone looking to quickly get a handle on happiness research in psychology. As with its distinguished forebear, the present volume provides thorough but accessible updates as to where psychological inquiry into the nature of hedonia is at, a smattering of useful contextualising comments from economists and other non-psychologists, and some discussion of where research might go next.