This study provides analyses of the childbearing behavior of female immigrants and their descendants in Spain. The study is based on two major surveys carried out in 2006 and 2007, the Fertility and Values Survey (2006) and the National Immigrants Survey (2007), which allow to compare the childbearing behavior of native, first generation and 1.5 generation immigrant women (who came to Spain at age 0-15). By means of event history techniques, we analyze the transition to first, second and third birth. Our analyses show that most groups of descendants to immigrants have similar or lower odds of parity transition than women with a full Spanish background, with the only exception of those coming from the Maghreb area. The lower odds of having the first child among 1.5 generation immigrant women should be interpreted as an indication of motherhood delay rather than an increased probability of childlessness, because the survival curves show that most women eventually make the transition to first birth. The risk of having a second and a third child is only significantly higher for the descendants of Moroccan immigrants compared to women with a full Spanish background. The results obtained partially reflect the intense selection involved in female migration inflows recently arrived to Spain, but also reveal an ongoing adaptation process of the reproductive behavior of the descendants of migrants to native fertility patterns. In addition, our findings confirm the importance of taking into account parity-specific differentials when studying the fertility of descendants of migrants, and to distinguish between quantum and tempo effects, especially when analyzing the transition to first birth. Moreover, our findings raise questions about two main issues: firstly, the potential contribution of immigrants to fertility recovery in countries with very-low fertility levels like Spain; and secondly, the slower assimilation of Moroccan origin immigrants into the mainstream fertility behavior, its causes and consequences.