From the abstract: "An infant or toddler can begin the process of receiving Part C early intervention services by having a diagnosed condition with a high probability of developmental delay (Individuals with Disabilities Education Improvement Act, 2004). How states define those diagnosed conditions that begin the initiation process varies widely. Lists of diagnosed conditions were collected from state Part C websites and Part C coordinators for a descriptive analysis. Across 49 states, the District of Columbia, and 4 territories, a final list of 620 unique conditions was compiled. No single condition was listed by all jurisdictions. Hearing impairment was the condition listed by the most states (n = 38), followed by fetal alcohol syndrome (n = 34). Of the 620 conditions, 168 (27%) were listed by only 1 state, 554 (89%) were listed by fewer than 10 states, and 66 (11%) were listed by 10 or more states. Of these 66 conditions, 47 (71%) were listed by fewer than 20 states. Most of these 66 conditions (n = 48; 72.7%) had a prevalence of "very rare or rare," 8 (12%) were "common," 6 (9%) were "very common," and 4 (6.1%) were "unknown." The wide heterogeneity in the number and type of diagnostic conditions listed across states should be further investigated as it may represent imbalances in children with diagnosed conditions gaining access to Part C evaluations and individualized family service plans and potentially the services themselves across states. In addition, providing ready access to lists of diagnosed conditions is a simple step that could help states and Part C programs facilitate access to services."