In the United States, paid advocates are usually members of the legal profession. In many arenas, lawyers enjoy a legally enforceable monopoly on such representation; in other arenas, lawyers share the advocacy function with other professionals, paraprofessionals, and laypersons. Recent research has raised questions about the wisdom of granting lawyers exclusive rights to deliver services such as advocacy. However, there has been no systematic research that has compared the work and performance of lawyer and nonlawyer advocates in contexts where both are permitted to appear. Using a "taxonomic theory of representation" as a conceptual framework, this study compares different types of advocates in four settings, using a combination of observation, structured interviews, and semi-structured interviews. The focus is on "case advocacy," as distinguished from "policy advocacy," involving both adversary and nonadversary (inquisitorial) processes. The study will evaluate the effectiveness of lawyers and non-lawyers, isolate the factors that determine the variable effectiveness of each type of advocate, and potentially demonstrate the advantages of getting away from the simple dichotomy of lawyers versus nonlawyers. Focusing on the question of the effectiveness of representation will not only advance theory in this area but will allow consideration of some of the foundational arguments that are used to justify the existence of the legal profession's monopoly on advocacy representation.