"The book under review provides a complete treatment of the principal-agent problem that covers all cases treated in economic literature ... . It is the first of its kind in that it provides a fully developed mathematical framework addressing the principal-agent problem with complete proofs and explanations of all mathematical tools used therein. ... The introduction of this book is accessible to a general audience." (Olympia Hadjiliadis, Bulletin of the American Mathematical Society, Vol. 52 (3), July, 2015) "The present book presents a nice exposition of the theory of the stochastic maximum principle, starting with BSDEs, and of its applications to contract theory. ... I recommend it to anyone working on or teaching the mathematical aspects of contract theory and/or stochastic control." (Etienne Pardoux, SIAM Review, Vol. 57 (2), June, 2015) "This book considers contract theory in continuous time. ... This book is a good reference book for researchers and graduate students in economic theory, finance and mathematical economics. Continuous-time contract theory is particularly useful in finance. This book provides a basic methodological framework, which can be used to develop further advances, both in applications and in theory." (Susheng Wang, Mathematical Reviews, August, 2013)