This paper considers methodological approaches that can help better understand inequity in healthcare, focusing on five key domains: availability, patient-centeredness, access, effectiveness, and implementation. We present conceptual definitions of each of these domains, example research questions pertaining to inequity in each domain, and methodological approaches that can contribute to research about health inequities. We discuss the role of multilevel, participatory, and longitudinal research, particularly using representative, real-world data. We propose alternatives to randomized controlled trials that better suit questions regarding inequities in healthcare. We discuss challenges and considerations for research on inequities in healthcare alongside opportunities for innovation and prioritization of methodologies that are underutilized in epidemiology and health services research. We emphasize throughout that each of these five domains are interconnected and essential to be understood jointly if we are to improve our understanding of the role of healthcare in perpetuating health inequities.