The Big 4 accounting firms have expanded their legal service arms to historic proportions over the last decade, employing thousands of lawyers around the world. Although most of the Big 4's revenue from legal services is presently generated outside the U.S., they are now making inroads into the U.S. legal market, and rule changes are being considered that would further allow the Big 4 to offer legal services in the U.S. This essay summarizes the current status of Big 4 firms as legal service providers, discusses potential implications of legal offerings for their U.S. audit practices, and suggests directions for future research. Our proposed research questions are informed by several literatures, interviews with former Big 4 partners and practicing attorneys, and a survey of the general public. They center on the fundamental difference between audit and law practices, brand equity considerations, and culture changes within the Big 4.