Severe problem behaviors, like aggression, self-injury, and repetitive behaviors, in people with intellectual and developmental disabilities often appear during early development and may persist without early intervention. The frequencies of self-injurious behavior, aggression, tantrums, property destruction and stereotyped behavior among 17 infants and toddlers at risk for developmental delays and severe behavior problems were assessed using two methods: 1) direct observation of responses during 10 s partial interval recording during analogue functional analysis and 2) the Behavior Problem Inventory-01 (BPI-01; Rojahn et al. Journal of Autism and Developmental Disorders, 31, 577-588, 2001), an informant rating scale. Analogue functional analysis results suggested that the most common function for problem behavior was automatic reinforcement, followed by negative reinforcement in the form of escape from demands. Agreement across the two types of measurement systems as to occurrence of the behaviors reported on the BPI-01 and direct observations during analogue functional analyses was greater than 75 % across aggression, self-injury, and stereotyped behavior. Agreement at a more molecular level of the ranking of the most commonly occurring specific behaviors was considerably lower. Results are discussed in terms of future research on identifying conditions that set the occasion for high levels of agreement between indirect and direct measurement systems for severe behavior problems. © 2014 Springer Science+Business Media New York.