Objective In the wake of a massive shift in public opinion on same‐sex marriage, scholars have examined the factors that predict support of marriage equality. This research, largely from cross‐sectional or trend data, leaves questionable evidence for causality. In this research note, we use newly available panel data to predict attitudes toward marriage equality. Methods We use three three‐wave panels of survey data from the General Social Survey (2006–2014) to estimate the effects of both time‐variant and nonvariant characteristics on attitudes toward marriage equality. Results Using time‐variant factors, we support prior research, finding evidence for the causal effect of political views and time period on attitudes. Unlike earlier research, we find no significant effect of church attendance or marital or parental status. Among invariant characteristics, we largely support prior research on the effect of demographic characteristics on attitudes. Conclusion This analysis underscores the importance of using longitudinal data to support causal inferences and augment cross‐sectional research on political attitudes.