Eligibility is the decision, made after an evaluation, about whether a child qualifies for special education under IDEA. It rests on two parts, and a child must meet both. First, the child must have a disability that fits one of the law's defined categories. Second — just as important — the disability must be such that the child needs special education because of it. A diagnosis alone does not automatically qualify a child.
That second part surprises many parents. A child can have a real, documented condition and still be found ineligible for an IEP if the team decides they do not need specialized instruction to make progress. In some of those cases a 504 plan is the better fit, providing accommodations without special education. The eligibility meeting is where the team weighs the evaluation data and makes this call together with you.
You are part of the eligibility team and an equal voice in it. Bring what you see at home, ask how each category and the "needs" question were considered, and request the decision in writing. If you disagree with the outcome — whether your child was found ineligible or placed in a category that does not fit — you can challenge it, including by requesting an independent evaluation.
General information and document preparation — not legal advice.