While end users these days seem happy with best-match text-retrieval systems, it appears that expert searchers still prefer exact-match (Boolean) text-retrieval systems by an overwhelming margin. This is somewhat surprising. Most expert searchers were probably trained with Boolean systems, and an obvious factor is simply preferring the familiar, but we argue that a second major factor is that these experts feel a much greater sense of control with Boolean than with best-match systems. We have designed a best-match system, MIRV, incorporating user-interface features that we believe will give experts a sense of control comparable to that of Boolean systems and that we believe end users will also be happy with. We implemented MIRV's document viewer and did a controlled user study, with encouraging results.