According to modernization theory, people will show greater variability over time in the order of making certain life transitions: getting a job, leaving the parental home, finding a partner, and becoming a parent. On the basis of hypotheses underlying generation theories - the relative scarcity hypothesis and the hypothesis of differential cohort socialization - more specific predictions can be made regarding the age at which various cohorts make a number of life transitions. Analysis of the life histories of 4098 Dutch people born since 1930 did not confirm the predictions of modernization theory. The predictions based on the relative scarcity hypothesis and the hypothesis of differential cohort socialization, in contrast, were generally verified. (1) The increasing level of education due to the economic recession in the 1970s can partly explain the increasing age at which the first job is obtained. (2) The age at which the parental home is left decreased primarily because students attending university or vocational colleges left home earlier. (3) The age of marriage decreased across the oldest cohorts and increased across more recent cohorts, which could be expected in light of the increased age at which jobs are obtained and the rise that has been observed in unmarried cohabitation. (4) Finally, the increase across cohorts in the age of becoming a parent is partially caused by the increasing age at which employment is obtained and the rise in unmarried cohabitation. In addition, the expectation was confirmed that the decline in the norms that married women should stop working for pay and promptly give birth to a child, in combination with the availability of effective contraceptive methods, resulted in a trend deflection in the age of becoming a parent for cohorts born since 1950.