Women politicians face barriers that can undermine their performance relative to men. Using original micro-data from Uganda, we test for gender gaps in performance across different job duties in subnational legislatures. We hypothesize, and find, that performance gender gaps are greatest in job duties that require greater peer interaction (legislative duties), while no such gaps exist in more individually-performed duties (e.g., meeting with the electorate, facilitating constituency development). Fine-grained network data reveals women’s informal exclusion in politician networks, and this exclusion holds explanatory power in explaining job duties requiring interaction with fellow politicians. Further, qualifications and previous experience also determine part of the gender performance gap in more intricate tasks. Moving forward, advocacy organizations may consider holding trainings and simulations with politicians on performing job duties in ways that encourage cross-gender professional network ties.