Engagement in Early Intervention (EI) and Early Childhood Special Education (ECSE) helps to support the development of very young children who might demonstrate delays or other challenges. Research documents underutilization of these essential childhood services. To understand how to increase engagement in EI and ECSE among eligible families, research is needed to identify barriers and facilitators associated with enrollment. The current study examined the relation between proposed barriers and service access outcomes (i.e., child age of delay identification, age at service provision, total number of EI/ECSE hours, and the total types of EI/ECSE services) reported by parents of birth to six-year olds (n = 60). Results revealed higher parent advocacy was significantly related to a younger age of service enrollment and a larger total number of intervention types used. This study is one of the first to provide quantitative evidence of specific barriers related to EI/ECSE enrollment. (author abstract)