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First readWhat to know+
Topic: What Intellectual Developmental Disability (IDD) means and who can helpWhat it affects: Learning, reasoning, communication, and daily self-care skillsWhen it starts: Must begin before age 18, from injury, illness, or brain differencesWho helps: The Harris Center for Mental Health and IDD in HoustonCrisis line: Call 713-970-7000 any time, day or night — sliding scale fees available
Next rungHow to step in+
Good first step: Act Harris Center Crisis and Access Line
Call 713-970-7000 and say: 'I need information about IDD services for someone in my family.'
Intellectual Disability (ID) — sometimes called Intellectual Developmental Disability (IDD) — affects how a person learns, reasons, and handles everyday tasks. The Harris Center for Mental Health and IDD breaks down what the diagnosis means, what causes it, and how Houston residents can get help, no matter their ability to pay.
ID is defined by two main areas of difficulty. The first is intellectual functioning — things like learning, reasoning, problem-solving, reading, writing, math, and memory. The second is adaptive behavior — the everyday skills a person needs to live, work, and connect with others, such as communication, self-care, social skills, and getting around the community. Both areas must show significant limits for a diagnosis to apply. Causes can include injury, illness, stroke, serious infection, or a brain problem that begins any time before age 18 — even before birth. For many children, no specific cause is ever found. It is also worth knowing that the Texas Administrative Code (TAC), the Texas Education Agency (TEA), and the DSM-5 (the national diagnostic handbook used by mental health professionals) each set slightly different standards. A diagnosis from a private psychologist or physician may not automatically meet the TAC standards used by state-funded services.
If you or someone you care about may have IDD or ID, start by talking with a doctor or licensed psychologist who knows Texas standards. Ask specifically whether the evaluation meets TAC requirements — especially if you plan to use state or school-based services. The Harris Center serves Houston-area residents on a sliding-scale fee schedule, meaning cost is based on what you can afford. Their 24/7 Crisis and Access Line is always staffed by counselors who can help you figure out next steps.
No fixed date
Not location-specific
If you are navigating IDD alongside mental health concerns, the Harris Center provides services for both. Houston families can also connect with local school districts for educational evaluations, which may use TEA standards that differ slightly from clinical or TAC criteria.
Understanding what IDD and ID mean can help you support a child, family member, or neighbor more effectively. Knowing the difference between diagnostic standards also helps you ask the right questions when working with schools, doctors, or service providers.
