This study investigated the Infant Behavior Record (IBR) as an observer-rated measure of temperament. The aim was to determine whether the IBR and a parent-rated measure of temperament were comparably associated with children's performance on laboratory tasks and with a measure of the home environment. We found several significant associations between the IBR and laboratory performance and no significant correlations between parent ratings and laboratory performance. Conversely, there were several significant associations between parent-rated temperament and the home environment and no significant associations between the IBR and the home environment. These findings lend evidence to the utility of the IBR as an observer-rated measure of temperament that can be used by teachers, clinicians, and other professionals working with children. Keywords temperament, observer ratings, parent ratings, early childhood Temperament can broadly be defined as traits of self-regulation, attention, activity, and affectivity that appear early in life and are thought to be influenced by both biological and environmental factors (Shiner et al., 2012). Many theoretically different temperamental constructs have been hypothesized, and different questionnaires capture different temperament factors (Shiner et al., 2012). In addition, there are several different methods of measuring temperament, with parentrated questionnaires of children's temperament typically used due to their cost-effectiveness and ease of distribution (Rothbart & Goldsmith, 1985). However, biases may exist in parents' ratings due to cognitive, personality, or experiential factors (Rothbart & Goldsmith, 1985). Few standardized observer-rated measures of temperament exist, and those that do exist are usually costly and time-consuming. The Infant Behavior Record (IBR; Bayley, 1969) was developed originally as a measure of behaviors observed during a clinical assessment situation, but has been used in previous studies as an observer-rated measure of temperament (Matheny, 1980, 1983; Rhea, DiLalla, & Cardon, 1990), can be completed quickly, and is predictive of later IQ (DiLalla et al.,