Long-term research with marked individuals shows that black-tailed, Gunnison's, and Utah prairie dogs (Sciuridae: Cynomys ludovicianus, C. gunnisoni, and C. parvidens) all reproduce slowly, despite claims of ranchers and early naturalists. Five factors are responsible for the slow reproduction. First, survivorship in the 1st year is <60% for all 3 species, and it remains low in later years. Second, even under optimal conditions, females of all 3 species produce only 1 litter/year. Third, the percentage of males that copulate as yearlings is only 6%, 24%, and 49% for black-tailed, Gunnison's, and Utah prairie dogs, respectively. The percentage of females that copulate as yearlings is only 35% for black-tailed prairie dogs, but it is 100% for both Gunnison's and Utah prairie dogs. Fourth, the probability of weaning a litter each year is only 43%, 82%, and 67% for female black-tailed, Gunnison's, and Utah prairie dogs, respectively. Fifth, for those females that wean offspring, mean litter size at 1st juvenile emergence from the nursery burrow is 3.08, 3.77, and 3.88 for black-tailed, Gunnison's, and Utah prairie dogs, respectively.