In this article we have brought together a collection of problems which were suggested at the Fourth Conference on Transport Theory.1It is hoped that the publication of these problems fulfills the dual purpose of (i) directing attention to gaps in the existing body of knowledge of transport theory, and (ii) stimulating research into new and hitherto unexplored areas of transport theory. Needless to say, the editor claims no responsibility for the correctness or incorrectness, solvability or in-solvability of any of the proposed problems. The sole responsibility rests with the proposer of each problem, whose name appears immediately after the title of the problem.