An evaluation was made of the language development component of Columbus, Ohio's All Day Kindergarten Program (ADKP). The ADKP was instituted in Columbus' public schools in January, 1972, to provide a full day of instruction for underachieving kindergarten pupils. The overall goal of the program was to prepare pupils for first grade by providing an extra half day of instruction to pupils needing additional help and attention. In the 1987-1988 school year, 18 teachers served in 18 Chapter 1 eligible elementary schools. Each provided daily instruction for two groups of 15 pupils. For evaluation purposes, the ADKP provided 123 days of instruction. Pupils included in the final pretest-posttest analysis attended at least 98 of those days. Data were collected in five areas: (1) pupil census; (2) standardized achievement test scores; (3) teacher census; (4) parent involvement data; and (5) inservice evaluation. The overall normal curve equivalent (NCE) gain for the program averaged 20.3 NCE points for the 6-month treatment or 3.4 NCE points for each month of treatment. Based on the evaluation results, it was strongly recommended that the ADKP be continued in the 1988-1989 school year. Results are discussed and specific steps for improving program effectiveness are described. Pupil and teacher census forms, parent involvement survey forms, and general and orientation inservice evaluation forms are appended. (RH)