To assess rates of incomplete specialty referral (referral not resulting in a specialist visit) and risk factors for incomplete referral in pediatric community health care centers.In this cross-sectional study, we used referral records and electronic health records to calculate rate of incomplete referral in 577 children referred from two health care centers in underserved communities to any of 19 pediatric specialties at an affiliated tertiary care center, over 7 months in 2008-2009. We used logistic regression to test the association of incomplete referral with child/family sociodemographic and health care system factors.Of the children, 30.2\% had an incomplete referral. Incomplete referral rates were similar at the two health care centers, but varied from 10\% to 73\% according to specialty clinic type. In multivariate analysis, sociodemographic factors of older child age, public insurance status, and no chronic health conditions correlated with incomplete referral, as did health care system factors of surgical specialty clinic type, low patient volume, longer wait for visit, and appointment rescheduling.Almost one-third of children referred to specialists were unable to complete the referral in a timely manner. To improve specialty access, health care organizations and policymakers should target support to families with high-risk children and remediate problematic health care system features.