In the past decade, Switzerland has experienced a large increase in the number of individuals going into early retirement. This paper examines the determinants of such early retirement using data from the newly implemented social-security module of the 2002 Swiss Labor Force Survey. In the sixteen-month period from January 2001 to April 2002, more than 36,000 older individuals, representing 8% of all workers within nine years of legal retirement age, became early retirees. One of the most important determinants of early retirement is the wage rate, yet its effect is not linear: both high and low wages reduce the probability. Other factors that play an important role include partner's employment status, education, industry, occupation, and coverage in the three social-security pillars. A major finding of this study is that about 30% of all early retirees continue working after retirement - and mostly for the same employer.