Despite recent periods of unified party control of government in Washington, DC, divided government has been the norm in recent decades. Scholars agree that when both presidential and congressional candidates are on the ballot the driving force behind divided government at the national level is split-ticket voting. In this study, I present a new psychological model of split-ticket voting. I posit that ticket splitting is motivated by ambivalence over the two major political parties. I test this partisan ambivalence explanation on split-ticket votes between president and Congress nationally between 1988 and 2004 and voting for state executive offices in Ohio in 1998. I find that partisan ambivalence predicts ticket splitting at both the national and state levels and does so about as well as some other explanations. The results of this study suggest that divided government occurs, in part, because voters are divided within themselves.