Recent years have witnessed a resurgence in the interest in family size intentions and ideals in developed societies, partially stemming from the idea that realized fertility in these societies is lower than intended fertility. This paper addresses the question of the stability of family size intentions. Based on Heckhausen’s life-span theory of control, it is hypothesized that young adults’ family size intentions are likely to change as a result of their experiences in the family and occupational life domains. To study this issue, data are used from a Dutch panel survey in which respondents are questioned on their family size intentions six times over the course of 18 years. The results show that family size intentions are not stable, but ...