Drawing on developmental networks theory, this qualitative research study explores the professional preparation and career decision-making processes of doctoral students in the sciences. The study is based on 95 semi-structured interviews with informants at three research universities in the United States. Though many students were interested in non-academic career tracks, they were largely unaware of the breadth of their choices or how to best prepare for these careers. Unable to cultivate networks in non-academic careers, many students turned to peers to fill the career development gap. Due to their lack of knowledge about career options, among other factors, students often delayed selecting and preparing for careers until the end of their graduate studies. Implications for doctoral education practice are discussed.