The focus of this report is the Direct Instruction Supervision Code, developed to assess the degree of implementation of the Direct Instruction Follow Through Model. Most of this paper deals with the development, reliability, concurrent validity, and criterion-related validity of the code, which is a classroom observation instrument. The report describes a Follow Through program assessment that employed the code, supervisor ratings, and Level-of-Use interviews. Findings indicate correlations between degree of implementation and gains in reading. Tables of data are appended. (MK)