  Participation of women in Open Source Software (OSS) is very unbalanced,
despite various efforts to improve diversity. This is concerning not only
because women do not get the chance of career and skill developments afforded
by OSS, but also because OSS projects suffer from a lack of diversity of
thoughts because of a lack of diversity in their projects. Studies that
characterize women's participation and investigate how to attract and retain
women are spread across multiple fields, including information systems,
software engineering, and social science. This paper systematically maps,
aggregates, and synthesizes the state-of-the-art on women's participation in
Open Source Software. It focuses on women's representation and the demographics
of women who contribute to OSS, how they contribute, the acceptance rates of
their contributions, their motivations and challenges, and strategies employed
by communities to attract and retain women. We identified 51 articles
(published between 2005 and 2021) that investigate women's participation in
OSS. According to the literature, women represent about 9.8\% of OSS
contributors; most of them are recent contributors, 20-37 years old, devote
less than 5h/week to OSS, and make both non-code and code contributions. Only
5\% of projects have women as core developers, and women author less than 5\%
of pull-requests but have similar or even higher rates of merge acceptance than
men. Besides learning new skills and altruism, reciprocity and kinship are
motivations especially relevant for women but can leave if they are not
compensated for their contributions. Women's challenges are mainly social,
including lack of peer parity and non-inclusive communication from a toxic
culture. The literature reports ten strategies, which were mapped to six of the
seven challenges. Based on these results, we provide guidelines for future
research and practice.
