When buying stocks, bonds, mutual funds, and other securities, individuals seeking advice typically turn to broker-dealers or investment advisers before they invest. In many cases, brokers and advisers perform similar functions but they are regulated differently under laws enacted during the Great Depression. Regulators are considering ways to harmonize the regulation of these professionals, but harmonization is fraught with difficulties. This chapter discusses the debate over harmonization and explains how the US Securities and Exchange Commission, the courts, and Congress have responded. The chapter concludes with insights into considerations that will likely determine how the harmonization debate will be resolved.