The focus of the paper is on better understanding volunteer retention. A broad-based survey of fourteen Australian nonprofit organizations develops an expanded quantitative model of volunteer retention by adding two new antecedents: values-congruency and altruistic motives to previous modeling. The study generates a more comprehensive set of rankings of volunteer retention motives, with altruism receiving top ranking. Using exploratory factor analysis, the study develops a new three-item perspective of altruism, combining helping, service and the cause. A new four-phase framework of the volunteer lifecycle is also developed. Investigating changes in retention motives over the life cycle reveals a major and unexpected finding, that the altruistic motive may actually become more important as volunteers move through the lifecycle.