Abstract Despite weak partisanship and considerable political change in the wake of the 2002 election, three-quarters of Brazilian voters supported a presidential candidate in 2006 from the same party they had backed in 2002. This article assesses the factors causing both electoral stability and electoral change with a transition model, a model testing whether the effects of respondents' evaluative criteria depend on their initial vote choices. Social context—personal discussion networks, neighborhood influences, and the interactions of social networks and municipal context—is the major force promoting stability and change, while the impact of partisanship is limited to a small share of voters.