Professional women with children are inundated with conflicting messages about how to manage their careers and personal lives and whether they should "opt in" or "opt out" of the workforce. Using in-depth interviews with 23 professional women, this study focused on the career choices that women make after having children. The authors found that many mothers neither opt in or opt out but successfully function in between these two choices, or opt "in between," by working flexible hours, by working part-time, and/or by being involved with home-based entrepreneurial endeavors. Using the boundaryless career typology of knowing why, knowing how, and knowing whom, the authors summarize the key strategies that mothers use to opt in between. The interviewees were clear about why they were working, managed their careers by finding the right organizational fit, did not focus on guilt or perfectionism, and maintained excellent networks of friends, bosses, colleagues, and day care providers. (Contains 1 table.)