In 2011, the US state of Mississippi mandated its school districts to adopt a sexuality education curriculum. Approximately half of districts chose a more comprehensive abstinence-plus curriculum over an abstinence-only curriculum. To understand this outcome, we conducted a logistic regression analysis of school district curriculum choice among Mississippi's school districts using data from 2012 when districts made the initial curricular decision, and from 2019, to assess continuity of findings. At both time points, poorer districts were more likely to adopt abstinence-plus curricula, despite the associated costs. Urban districts were also significantly more likely to choose abstinence-plus curricula, as were districts connected to Mississippi First, a local non-profit organisation that linked school districts to federal funding for abstinence-plus curricula. Despite the connection between political and sexual liberalism, political liberalism had limited predictive power over district sexuality education curriculum choice. Furthermore, one-third of the districts that adopted abstinence-only curricula were very similar to those that adopted abstinence-plus curricula in terms of poverty, religious adherents, rural location, political liberalism, gonorrhoea burden and racial composition. These findings indicate the importance of state mandates for sexuality education, federal funding for evidence-based curricula, and the presence of supportive local organisations to advance the adoption of more comprehensive sexuality education.