Background: Depressive and anxiety disorders are among the top ten leading causes of disabilities. We know little, however, about the onset, developmental course and early risk factors for depressive and anxiety symptoms (DAS). Objective: Model the developmental trajectories of DAS during early childhood and to identify risk factors for atypically high DAS. Method: Group-based developmental trajectories of DAS conditional on risk factors were estimated from annual maternal ratings (1 1/2 to 5 years) in a large population sample (n = 1759). Results: DAS increased substantially in two of the three distinct trajectory groups identified: High-Rising (14.7%); Moderate-Rising (55.4%); and Low (29.9%). Two factors distinguished the High-Rising group from the other two: Difficult temperament at 5 months (High-Rising vs Moderate-Rising: OR = 1.32; 95% CI = 1.13-1.55; High-Rising vs Low: OR = 1.31, CI = 1.12-1.54) and maternal lifetime major depression (High-Rising vs Moderate-Rising: OR = 1.10; CI = 1.01-1.20; High-Rising vs Low: OR = 1.19; CI = 1.08-1.31). Two factors distinguished the High-Rising group from the Low group: High family dysfunction (OR = 1.24; CI = 1.03-1.5) and Low parental self-efficacy (OR = 0.71; CI = 0.54-0.94). Conclusions: DAS tend to increase in frequency over the first 5 years of life. Atypically high level can be predicted from mother and child characteristics present before 6 months of age. Preventive interventions should be experimented with at risk infants and parents.