Contract theory which emphasizes the importance of unverifiable actions and private
information has been a highly active field of research in microeconomics in the last decades.
This thesis is divided into two parts. Part I consists of three chapters that study
contract-theoretic models which are motivated by the classic procurement problem of a principal
who wants an agent to deliver a certain good or service. In such models it is typically assumed
that decision makers are interested in their own monetary payoffs only. Moreover they have
unlimited cognitive abilities and behave in a perfectly rational way. Yet in practice people
often do not behave this way. While empirical research is very difficult in contract theory
laboratory experiments have recently turned out to be an important source of data. In Part II
three experimental studies are presented that investigate contract-theoretic problems brought
up in Part I.
