From the BoardSource website:

BoardSource has long recognized the critical role that boards play in overseeing their organizations’ mission, finance, and strategic direction.

With nearly 25 years of hands-on experience working with nonprofit boards, BoardSource has become the go-to resource for funders, partners, and nonprofit leaders who want to magnify their impact within their community through exceptional governance practices.

BoardSource supports a community of more than 60,000 individuals with customized diagnostics, live and virtual trainings, and a comprehensive library of governance resources that includes original publications. BoardSource is a 501(c)(3) organization.