Background and Context: Despite over 30 years of research on broadening participation, women are still underrepresented in Computer Science (CS) education. While enrolment in CS majors has increased, women earn only 18% of the CS baccalaureate degrees in the US. Objective: Most research focuses on why women leave CS. This study explores factors (i.e. social interactions and practices) that support retention from the perspective of women who persisted in their CS major. Methods: We interviewed ten participants first by separating them in two focus groups and then by using individual in-depth interviews. Findings: We identified four types of social interactions that support retention of women. In terms of practices, we present four of the most frequent practices, and four practices that characterised retention of women at the periphery. These findings add nuanced understanding of factors that support retention of women through the theoretical lens of legitimate peripheral participation in communities of practice. Implications: This study has several implications for CS departments on how they can support women's retention, such as by supporting internships, propagating work-life balance and training faculty and students on the importance of legitimacy and support.