So far, we have shown how logical dynamics deals with agents' knowledge and beliefs, and informational events that change these. But as we noted in Chapter 1, agency also involves a second major system, not of information but of evaluation. It is values mixed with information that provide the driving force for rational action – and the colour of life. The barest record of evaluation are agents' preferences between worlds or actions. Thus, the next task in this book is dealing with preferences, and how they change under triggers like suggestions or commands. While this topic seems different in flavour from earlier ones, properly viewed, it yields to the same techniques as in Chapters 3, 7. Therefore, we will present our dynamic logics with a lighter touch, while emphasizing further interesting features of preference that make it special from a logical perspective.