Rationale: It is not clear to what extent behavior problems observed in children with asthma antecede asthma development, or are a consequence of the disease. Objectives: We investigated psychologic factors at age 3 years and subsequent development of wheeze by age 5 in an unselected birth cohort study. Children were recruited prenatally, followed prospectively, and reviewed at age 3 and 5 years. The rate of significant behavior problems at age 3 (above the clinically relevant cut-off on the Eyberg Child Behavior Inventory) was compared between children who had never wheezed (n = 397) and those developing late-onset wheezing (after age 3 years; n = 39). Late-onset wheezers were more likely to be above cut-offs for behavior problems at 3 years (before wheeze onset), compared with children who never wheezed, on Intensity (23.1% vs. 6.0%, p <0.001) and Problem scores (10.8% vs. 1.3%, p <0.001). Families of late-onset wheezers had poorer scores on family functioning variables, but we found no evidence of increased anxiety or depression scores in parents. In the multivariate analysis, significant and independent associates of late-onset wheeze were as follows: maternal asthma (odds ratio [OR] 5.4, 95% confidence intervals [CI] 2.1-13.8, p <0.001), maternal smoking when child was 3 years (OR 3.3, CI 1.2-8.7, p = 0.02), expressiveness (OR 0.71, CI 0.55-0.9, p = 0.005), and significant behavior problems at age 3 years (OR 3.5, CI 1.2-9.9, p = 0.02). Conclusions: Behavior problems in early life are associated with increased risk of subsequent development of wheeze.