This article explores four pressing analytical challenges in fiduciary law. The problems are exposed by seeking answers to the pointed “who, what, and so what?” questions on fiduciaries. In short, “Who is a fiduciary?” and just how far does this protective jurisdiction stretch. Secondly, “What distinctive obligations rest on a fiduciary’s shoulders?” — what is it that defines and sets apart the fiduciary regime, providing it with mechanisms which differ from the routine restrictions applying to anyone who acts for others? And, finally, “What particular and distinguishing consequences follow upon a breach of these special restrictions?” This last question breaks down into two familiar but seemingly intractable parts: when and how do profits need to be disgorged; and when and how do losses need to be compensated? The answers to these four questions have never proved easy, yet these are the questions we must answer. Here it is suggested that a tightly rationalised (and, as it turns out, rather narrow) answer to the first question leads inescapably to more readily defensible answ ers to the three questions which follow it.