People decide about political parties by taking into account the preferences, values, expectations, and perceptions of their family, friends, colleagues, and neighbors. As most persons live with others, members of their households influence each other's political decisions. How and what they think about politics and what they do are the outcomes of social processes. Analyzing data from extensive German and British household surveys, this book shows that wives and husbands influence each other; young adults influence their parents, especially their mothers. Wives and mothers sit at the center of households: their partisanship influences the partisanship of everyone else, and the others affect them.