OBJECTIVES: To document the natural history of stuttering by age 4 years, including (1) cumulative incidence of onset, (2) 12-month recovery status, (3) predictors of stuttering onset and recovery, and (4) potential comorbidities. The study cohort was a prospective community-ascertained cohort (the Early Language in Victoria Study) from Melbourne, Australia, of 4-year-old children (n = 1619; recruited at age 8 months) and their mothers. METHODS: Outcome was stuttering onset by age 4 years and recovery within 12 months of onset, defined using concurrent monthly parent and speech pathologist ratings. Potential predictors: child gender, birth weight, birth order, prematurity, and twinning; maternal mental health and education; socioeconomic status; and family history of stuttering. Potential comorbidities: preonset and concurrent temperament, language, nonverbal cognition, and health-related quality of life. RESULTS: By age 4 years, the cumulative incidence of stuttering onset was 11.2% (95% confidence interval [CI]: 9.7% to 12.8%). Higher maternal education (P = .004), male gender (P = .02), and twinning (P = .005) predicted stuttering onset. At outcome, stuttering children had stronger language (mean [SD]: 105.0 [13.0] vs 99.6 [14.6]; mean difference 5.5, 95% CI: 3.1 to 7.8; P < .001) and nonverbal cognition (mean [SD]: 106.5 [11.4] vs 103.9 [13.7], mean difference 2.6, 95% CI: 0.4 to 4.8; P = .02) and better health-related quality of life but were otherwise similar to their nonstuttering peers. Only 9 of 142 children (6.3%; 95% CI: 2.9% to 11.7%) recovered within 12 months of onset. CONCLUSIONS: Although stuttering onset is common in preschoolers, adverse affects are not the norm in the first year after onset.