A survey of Wikipedia editors from 2011 found that 90% were male, 9% were female, and 1% were transgender, demonstrating a significant gender gap among contributors. On average, Wikipedia contributors are 31-year old, straight, white males with a college degree. The presentation discusses the multiple layers of bias that contribute to the gender gap, including language bias and underrepresentation of topics related to women. It also describes current projects aimed at addressing the gender gap on Wikipedia and Wikidata.