An extensive literature links language problems with behavioral difficulties and academic underachievement. Although less extensive, emerging literature suggests that temperament, Positive Affectivity (PA) in particular, contributes to language development. Thus, the present study was focused on PA related temperament dimensions in infancy as predictors of early expressive language. Mothers (N=148) were recruited and administered a temperament questionnaire when their infants were 8 and 12 months of age. PA scales: Activity (ACT), Smiling & Laughter (SL), High-Intensity Pleasure (HP), Perceptual Sensitivity (PS), Approach (APP), and Vocal Reactivity (VR) were considered. A follow-up evaluation addressing language development -- vocabulary and phrase length, was conducted at 24 months of age (n=85). Length of phrases positively correlated with PS and APP at 8 and 12 months, and VR at 8 months. Infants' vocabulary score was positively correlated with PS at 8 months and 12 months, and APP at 12 months. Further hierarchical multiple regression analyses indicated that ACT and APP at 8- months uniquely predicted phrase length, whereas PS and APP of 8-month infants contributed to later vocabulary scores. PS at 12-months predicted vocabulary scores, after accounting for covariates and other PA attributes.