This is the first philosophical study of artifacts that is book length. In it Randall Dipert develops a theory of what artifacts are and applies it extensively to one of the most complex and intriguing kind of artifacts, art works. He presents his own account of what agents, intentions, and actions are, then uses these notions to clarify what it is for an agent to "make" something. From this starting point, he develops a full theory of artifacts and other artificial things - and, especially, a theory of art works and performances of art works as artifacts. He proposes a theory of nature and of the value of nature as what is essentially nonartificial. Two chapters are devoted to value considerations: merit in artifacts generally, and the evaluation of art works and performance art as artifacts or intentional gestures. Believing that a developed theory of action and philosophy of mind is necessary for a developed aesthetics and philosophy of art, Dipert relies on classical and contemporary research on agency, actions, and intentions, and on the intentionalist theory of mental objects of Brentano and Meinong. Dipert considers artifacts to be physical entities, but he also includes in the definition thoughts, utterances, and performances. This vast category encompasses everyday household objects and tools, streets and edifices, as well as communicative and artistic artifacts. Especially with regard to artistic artifacts, Dipert proposes a theory of expression and communication as actions and extensively discusses the problems of interpreting and recognizing actions, artifacts, and art works.