This is a textbook introducing selected topics in formal social choice theory. Social choice theory studies group choices that are based on information about preferences of members of the group (voting rules being one important special case). This involves economics, which provides the method of modelling individual decision making, political philosophy, which provides criteria about the allocation of decision-influencing power, and game theory, which provides a framework for thinking about the strategies individuals employ in trying to influence the group choice. The goal of this book is to take basic ideas like impossibility theorems, rights exercising and strategy proofness and give the student just enough technical background to be able to understand these ideas in a logically rigorous way. This is done through a set of 250 exercises that constitute the heart of the book and which differentiate this book from all other texts in social choice theory.