The Stanford Behavior Design Lab (formerly known as the Stanford Persuasive Technology Lab and Stanford Captology Lab) is a research organization advancing behavior change methods and models based at Stanford University. Founded in 1998 and directed by B. J. Fogg, the Behavior Design Lab is an interdisciplinary team of Stanford students, recent graduates, and quantitative researchers who study factors that impact human behavior, conduct IRB research, share insights, and create practical solutions that make people happier and healthier. The team is the global authority in a new and systematic way to design for behavior change, an approach called “Behavior Design”. The Lab manager is Tanna Drapkin

With an emphasis on health, productivity, and financial well-being, the Behavior Design Lab performs research and trains Fortune 500 companies on the use of Computing Technology and Behavior Design to facilitate positive behavior change in product design and new product development (Instagram, Goodyear Tire).

The Lab is best known as the mobile health and start-up Lab at Stanford University, having been the inception of concepts for big name companies such as Instagram, Facebook Apps, and Clubhouse among others. The Lab's alumni network is extensive, deeply rooted, and has actively driven, participated, advised, and/or invested in multiple successful Silicon Valley unicorns and Fortune 500 companies.

The Behavior Design Lab's mission is to "teach good people how human behavior works so they can create solutions that effectively increase health, boost happiness, and promote human flourishing."