The classical sociology of parties was born alongside parties themselves. It explored their dynamic interrelationships with states and society, as well as the tensions inherent in the fact that parties are simultaneously representatives and power seekers. Despite these rich foundations, from the 1960s the sociological approach came to be narrowly identified with a one-dimensional conception of parties, and political sociologists focused their attention elsewhere. This review contributes to efforts that began in the 1990s to reclaim the political party as a full-fledged sociological object. To this end, we track the hourglass-shaped trajectory of the sociology of parties: from broad Marxian and Weberian roots, to narrowing and near-eclipse after the 1960s, to a reemergence that reclaims the breadth of the classical traditions. We conclude by suggesting six lines of inquiry that we believe would be fruitful, emphasizing both classical concerns that deserve more attention and innovative approaches that point in novel directions.