Caltech Women in Physics, Math and Astronomy (WiPMA) aims to support undergraduate, graduate and postdoc women in the PMA division by creating an inclusive community and providing opportunities for professional and personal development. We achieve this by inviting speakers to campus, hosting workshops, discussing peer-reviewed articles on gender in STEM, and holding social events for all women and allies in PMA. Our group is open to all undergraduate, graduate, postdoc, faculty, and staff members who identify as women in PMA. We use an inclusive definition of "woman" and "female" and we welcome trans women, genderqueer women and non-binary people. WiPMA is a student-lead initiative, started in its entirety in Fall 2016 with the support of the PMA division and the Caltech Center for Diversity. Spring 2017 is our first official term of programming. Here, we present a description of our group and its mission, and outline the basic steps involved in starting such a group on a university campus. In addition, we present statistics concerning our membership base and attendance at our events thus far. Ivanna Escala NSF/Ford Graduate Fellow | Caltech Astronomy | astro.caltech.edu/~ie/