This volume contains the papers and commentaries presented at the fourth philosophy colloquium at the University of Western Ontario in November 1968. The papers examine, from different points of view, the central problems in the philosophy of action. They include: "Agency" by Donald Davidson with comments by James Cornman; "On the Logic on International Action" by Roderick Chisholm with comments by Bruce Aune and a reply by Roderick Chisholm; "Wanting: Some Pitfalls" by R.M. Hare with comments by David Gauthier and D.F. Pears; "Two Problems about Reasons for Actions" by D.F. Pears with comments by Irving Thalberg. Also included is an extensive bibliography of recent work in the philosophy of action. The contributors are all well known for their work in this branch of philosophy; their papers present a cross section of the best work being done in the area at the present time.