My research focuses on the relationship between political parties and public opinion, and the implications of this for the electoral process. This relates to a number of questions of central importance to democratic theory, including where public opinion comes from. Why does it change over time? Do elections compel parties to adopt policies consistent with public opinion? How do parties adapt to changes in public opinion over time? How do long term relationships develop between political parties and particular groups of voters? My research on these questions can be grouped into three general themes: (1) party behavior and its implications for democracy; (2) the historical development of party systems; and (3) the nature and origins of public opinion.