The 'terrible twos' are often associated with increased temper tantrums, noncompliance and aggression. Although some expression of these behaviors is normal, whether early individual factors can predict which children are most at risk of frequent or prolonged emotional and behavioral problems is of increasing interest. The current study of 6,067 toddlers found that their 9 month scores on a new brief measure of temperament--the Infant Behavior Questionnaire- Revised Very Short Form (IBQ-R-VSF)--were associated with both difficult behaviors and prosocial behaviors at age 2, measured using a preschool version of the Strengths and Difficulties Questionnaire. Controlling for a range of demographic, maternal characteristics and contextual factors, we found that infants higher on the trait Negative Emotionality and/ or lower on Orienting Capacity and Fear were more likely to develop hyperactivity, emotion, peer and conduct problems and less likely to demonstrate pro-social behaviors at two years of age. Temperament aged 9 months explained an additional 1-6 % of the variance in toddler behavior. These findings suggest that infant temperament is associated with the behavior strengths and difficulties of 2-year-olds and provide the first longitudinal validation of the new 5-factor structure of the new IBQ-R-VSF.