The purpose of the present study was to discriminate between the 2 dominant perspectives governing research on the nature of marital change over the transition to parenthood. Progress can be made in understanding this transition by recognizing the role of uncontrolled sources of variability in research designs, defining and using control groups, and timing of data collection around the child's arrival, and the authors conducted a study incorporating these methodological refinements. Growth curve analyses were conducted on marital satisfaction data collected twice before and twice after the birth of the 1st child and at corresponding points for voluntarily childless couples (N = 156 couples). Spouses who were more satisfied prior to pregnancy had children relatively early in marriage, and parents experienced greater declines in marital satisfaction compared to nonparents. Couples with planned pregnancies had higher prepregnancy satisfaction scores, and planning slowed husbands' (but not wives') postpartum declines. In sum, parenthood hastens marital decline--even among relatively satisfied couples who select themselves into this transition--but planning status and prepregnancy marital satisfaction generally protect marriages from these declines.