Data in life table form are presented from a 12-year prospective study of 859 children on the age of attaining bladder control for waking and sleeping hours by three indices: (1) age of initial dryness, (2) age of final dryness, and (3) the prevalence of dryness. By use of these indices the large contribution of relapsers to enuresis is seen. The prevalence of bedwetting in the study population was greater than that reported in other studies; the validity of this finding is defended. A larger proportion of female than male children attained both day and night dryness during the first 2 years of life. The percentage of Negro boys who first attained dryness was less than that of the other three race-sex groups after 2 years of age and was significantly less than that of Negro girls until 9 years of age. One quarter of the 817 children who attained initial nighttime dryness by age 12 relapsed; these relapsing episodes had a median duration of 2.5 years. One tenth of 855 children who attained initial daytime dryness had relapses, and the median length of these was 1.2 years. Relapsing occurred much more frequently in Negro than Caucasian children; it also was seen more often in Caucasian males than in Caucasian females. Low birth weight children had a higher percentage of children wet for both waking and sleeping hours than did full birth weight children.