The category of "speech or language impairment" (commonly referred to as "SLI") accounts for the second highest numbers in terms of students served in special education. (Source: Digest of Education Statistics: 2010). A speech or language impairment is, most simply put, a disorder in the area of communication. While there are diagnostic criteria used by licensed pathologists and psychologist to diagnose a child with a Language Disorder, the eligibility criteria, like all categories, is set by the IDEA and state law and does not rely on exactly the same standards.
IDEA defines a speech or language impairment as a communication disorder, such as stuttering, impaired articulation, a language impairment, or a voice impairment, that adversely affects a child's educational performance. 34 C.F.R. section 300.8. State laws will have more specific criteria for how to determine if a child presents with such an impairment and qualifies for special education and related services.
Example of State Criteria:
In California, the Education Code sets forth the following criteria for eligibility under the category of SLI:
(c) A pupil has a language or speech disorder as defined in Section 56333 of the Education Code, and it is determined that the pupil's disorder meets one or more of the following criteria:
(1) Articulation disorder.
(A) The pupil displays reduced intelligibility or an inability to use the speech mechanism which significantly interferes with communication and attracts adverse attention. Significant interference in communication occurs when the pupil's production of single or multiple speech sounds on a developmental scale of articulation competency is below that expected for his or her chronological age or developmental level, and which adversely affects educational performance.
(B) A pupil does not meet the criteria for an articulation disorder if the sole assessed disability is an abnormal swallowing pattern.
(2) Abnormal Voice. A pupil has an abnormal voice which is characterized by persistent, defective voice quality, pitch, or loudness.
(3) Fluency Disorders. A pupil has a fluency disorder when the flow of verbal expression including rate and rhythm adversely affects communication between the pupil and listener.
(4) Language Disorder. The pupil has an expressive or receptive language disorder when he or she meets one of the following criteria:
(A) The pupil scores at least 1.5 standard deviations below the mean, or below the 7th percentile, for his or her chronological age or developmental level on two or more standardized tests in one or more of the following areas of language development: morphology, syntax, semantics, or pragmatics. When standardized tests are considered to be invalid for the specific pupil, the expected language performance level shall be determined by alternative means as specified on the assessment plan, or
(B) The pupil scores at least 1.5 standard deviations below the mean or the score is below the 7th percentile for his or her chronological age or developmental level on one or more standardized tests in one of the areas listed in subsection (A) and displays inappropriate or inadequate usage of expressive or receptive language as measured by a representative spontaneous or elicited language sample of a minimum of fifty utterances. The language sample must be recorded or transcribed and analyzed, and the results included in the assessment report. If the pupil is unable to produce this sample, the language, speech, and hearing specialist shall document why a fifty utterance sample was not obtainable and the contexts in which attempts were made to elicit the sample. When standardized tests are considered to be invalid for the specific pupil, the expected language performance level shall be determined by alternative means as specified in the assessment plan.
(Source: Title 5, California Code of Regulations, Section 3030(c))
Other states also have criteria that is based on sub-dividing this category into specific impairments that include fluency disorders, voice disorders, articulation disorders and language disorders. For a sampling, see these state's websites:
Things to keep in mind:
SLI is not just about articulation. Many school districts are good at identifying the students who strictly fall within the "articulation" category of impairment, but have more difficulty when it comes to adequately and comprehensively assessing students to identify the more subjective and complex language disorders. This is something you should look out for starting with the assessment plan itself - be proactive and make sure your school district is also looking at the broader language and communication issues including receptive language, expressive language, pragmatics / social language, etc.
Eligibility under the category of SLI versus the need for speech and language services:
Here in California, a problem that we often face is the misunderstanding amongst school district speech therapists regarding how to apply the eligibility criteria. The eligibility criteria has a lot of specificity of the criteria in terms of how far below the mean a student's scores must fall. School districts often mistakenly assert that this criteria is what must be met for a student to receive speech and language therapy as a related service. In other words, even if a student is already eligible, or is being made eligible, for special education under another category, such as Autism or SLD, a school district may say that they cannot receive speech therapy as a related service if they do not also meet the criteria for eligibility under the category of SLI. This is a mistaken analysis, as these are two entirely separate issues. One issue is whether a student is eligible under SLI as their category of eligibility. The other is whether they require speech therapy as a related services to meet their unique needs arising from their disability. Once a child is eligible for special education and related services under any category, the school district is obligated to offer and provide a program that meets their unique needs and provides them and educational benefit.
The American Speech and Hearing Association (ASHA) is a go-to source of information regarding speech and language impairments and related issues. Their article about eligibility for special education can be found on their website (click here).