Gendered attrition from STEM jobs further exacerbate the gender wage gap.  We explore the role employment conditions – specifically long work hours cultures encouraged in STEM – play in shaping occupational attachment among a cohort of recent college graduates with Chemical Engineering degrees. Using three waves of annual in-depth interviews with 51 respondents we investigate how work hour norms, increasing responsibility, and hours variability shapes orientations towards STEM employment.  In their first year, most respondents worked regular hours. But nearly forty percent engaged in overwork (50+ hours per week) or experienced extreme variability in hours.  Women more often experienced extreme hours variation than men, who more frequently engaged in overwork.  By year three, the proportion working long hours increased.  Both men and women express concerns over how to achieve a better work-life balance, but the dissonance between desires for limited work hours and workplace expectations were particularly problematic for women.