It is unclear to what extent general developmental/behavioral assessments are performed, if screening for autism spectrum disorders (ASDs) is being conducted, and what the barriers to providing such assessments are in routine pediatric practice. Therefore, this study examines (1) the factors influencing the use of general developmental and autism-specific screening tools in primary care pediatric practice, (2) the barriers to providing these assessments, and (3) pediatricians' beliefs regarding ASD prevalence. A cross-sectional survey was mailed in June 2004 to a 60% (n = 1119) random sample of Maryland and Delaware licensed pediatricians. In August 2004, a second mailing was sent to nonrespondents. A total of 471 (42%) of the surveys were returned, and of those, 255 (54%) who practiced in general primary care were eligible. The sample was 47% male, 69% had more than 14 years' experience, 71% were in private practices, and 56% had fewer than 10 ASD patients. Most (82%) routinely screened for general developmental delays, but only 8% screened for ASD. The main reasons reported for not screening for ASD were lack of familiarity with tools (62%), referred to a specialist (47%), or not enough time (32%). Most specialist referrals (77%) were to a developmental pediatrician. Most pediatricians (71%) believed that ASD prevalence has increased, and nearly all attributed this to changes in diagnostic criteria and treatment. Service system limitations must be overcome to increase awareness and familiarity with screening tools, provide sufficient time and resources, improve screening, and enhance provider education.