Bay Area Derby, formerly B.ay A.rea D.erby Girls, is a women's flat-track roller derby league based in the San Francisco Bay Area. Bay Area Derby (BAD) was founded in 2004 and is a founding member of the Women's Flat Track Derby Association (WFTDA). BAD is a skater-owned and -operated 501(c)(3) non-profit league. The league is composed of four teams for intra-league play, and an all-star travel team that competes nationally. As of 2016, BAD was ranked in the top 20 overall in WFTDA.