This page compares two distinct NUCC-taxonomy specialties tracked by the CMS National Plan and Provider Enumeration System: Environmental Modification Occupational Therapy Assistant, which currently counts 145 enrolled providers across 38 U.S. states and territories, and Occupational Therapy Assistant, with 41,034 providers across 54 states. Each clinician on these rosters selected a primary NUCC code at NPI enrollment, so the totals measure how many providers self-identify their primary practice as Environmental Modification Occupational Therapy Assistant or Occupational Therapy Assistant rather than the total population ever trained or credentialed in either field — dual-certified clinicians show up under whichever code they registered first.

On national volume, Occupational Therapy Assistant carries the larger provider roster (41,034 vs 145), and Occupational Therapy Assistant has the wider geographic footprint at 54 states versus 38. The top Environmental Modification Occupational Therapy Assistant concentration sits in Texas (20 providers), while Occupational Therapy Assistant peaks in Texas (4,228). The per-capita columns in the table below normalize each state's raw count against 2023 Census population estimates, which matters because absolute provider counts track population scale first and specialty density second — a small state with a strong training pipeline can out-rank a larger state on per-100K availability.

Use this comparison to understand relative availability, not to judge clinical substitutability — Environmental Modification Occupational Therapy Assistant and Occupational Therapy Assistant are distinct specialties with different scopes of practice, training requirements, and conditions they treat, even when their NUCC categories overlap. Important: PlainDoctor is a directory of publicly available CMS government data, not medical advice, a provider rating, or a recommendation about which specialty a patient should consult. Always work with a licensed clinician to determine which specialty is appropriate for your condition, verify any specific provider through the NPPES NPI Registry and the relevant state medical board, and consult the NUCC taxonomy documentation for the formal scope-of-practice definitions behind each specialty code.