The NIH defines a clinical trial as a research study in which one or more human subjects are prospectively assigned to one or more interventions (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes. Clinical trials range from small, first-in-human, tolerability or exploratory studies, to larger trials of efficacy or effectiveness. The NIAMS clinical trials program is designed to support the spectrum of such studies with funding mechanisms tailored to different levels of complexity and risk.