Illinois Inventory — 131 (ILI-131) is a comprehensive assessment tool designed to measure the functional strengths and weaknesses of individuals of all ages. The ILI-131 consists of 131 items on six scales that evaluate an individual’s current functioning across multiple domains, including general intellectual functioning, academic skills, adaptive behavior, social/emotional functioning, and executive functioning. The ILI-131 is divided into four versions: the Adult Version, the Adolescent Version, the Child Version, and the Preschool Version. Each version assesses the same domains, but with age-appropriate items tailored to the developmental level of the individual being assessed. The ILI-131 is a reliable and valid measure of an individual’s current abilities and can be used for a variety of purposes, including educational, clinical, and research applications.