As part of the Ability Development Project to identify 4-year-old Mexican American children with learning disabilities and develop appropriate curricular materials for them, 99 children (3-5 years old) attending city day care centers were assigned to the Bilingual Early Childhood Program, Level II. Twenty-nine children (final results included data on only 22 of this group) identified by Project staff as having the most severe learning disabilities were selected as the target population. Identification instruments and supplementary activities were developed or adapted using a pre-posttest research design which compared results from the target group with results from non-handicapped classmates and handicapped children who had not received supplementary assistance. The following products resulted: Spanish/English Language Preference Screening, Observational Checklists for Referral, Criterion Referenced Test, Supplementary Activities, the Instructional materials manual "How to Fill Your Toy Shelves Without Emptying Your Pocketbook--70 Inexpensive Things to Do or Make", and a manual on working with parents of handicapped children. Findings included that project children made significant gains on criterion-referenced and norm-referenced tests; and target children who had received Supplementary Activities made greater gains than target children who had not, and in some areas made gains comparable with those of their non-handicapped peers. (Numerous tables with statistical information are provided.) (Author/SB)