Numerous studies indicated that agreement between parent and teacher ratings of symptoms of attention-deficit/hyperactivity disorder in children of all ages is poor, but few studies have examined the factors that may be associated with rater differences. The present study examined the contextual, parent, parenting, and child factors associated with rater differences in a community sample of 4-year-old children. Parents and teachers of 344 4-year-olds recruited from preschools and pediatric practices completed the preschool versions of the Child Symptom Inventory. Measures of socioeconomic status, family stress and conflict, caretaker depression, parental hostility, support-engagement, and scaffolding skills, and child negative affect (NA), sensory regulation (SR), effortful control (EC), inhibitory control, and attachment security were obtained either by parental report or observational measures. chi 2 difference tests indicated that child factors of EC and SR, and contextual factor of stress and conflict, contributed more to parent-ratings of ADHD-I and ADHD-HI than to teacher-ratings of those same types of symptoms. Two factors contributed more to teacher-than to parent-rated ADHD-I, NA and caretaker depression. Results indicate there are differences in factors associated with ADHD symptoms at home and school, and have implications for models of ADHD.