The Brazilian Electoral Panel Study (BEPS) was designed primarily to capture campaign dynamics at the national level during the 2010 Brazilian presidential election. It aimed at generating data that make it possible to i) measure electoral volatility at the individual level during political campaigns, and ii) explore the ways in which both short and long-term factors affect this process and the ultimate vote decision. The Brazilian Electoral Panel Study is composed of three waves conducted in March and April, August, and November of 2010. The first wave was implemented about six months prior to the first round of the election and before the official launch of the political campaign that began in July with the nomination of candidates. It was conducted as part of the 2010 AmericasBarometer of the Latin American Public Opinion Project (LAPOP). Wave Two of the survey predated the beginning of the Free Electoral Airtime (Hor√°rio Gratuito de Propaganda Eleitoral or HGPE), in which candidates for all offices have 45 minutes of daily access to television broadcasting during prime-time hours. Finally, Wave Three was carried out immediately after the second round of the election, which occurred on October 31. The panel sought to establish baseline measures of vote intention, policy preferences, and several related factors, following longstanding debates on electoral behavior in Latin America and the United States.