This study was an effort to determine the psychometric properties of an instrument designed to measure a student's previous opportunities to learn from reading instruction. This instrument (Teachers' Implementation of Scientifically Based Reading Instruction (TISBRI)) is based on Porter and Smithson's (2001) framework for systematically evaluating opportunities to learn, and its content stems from Put Reading First: The Research Building Blocks for Teaching Children to Read (Armbruster, Lehr & Osborn, 2001). The pilot version of the TISBRI was administered to 19 teachers who rated the reading instruction they had delivered to a single student in their class since the beginning of the school year. Item analyses, reliability, and validity studies were conducted to determine the merits of the instrument and refine it for future use. The instrument showed promise for having strong internal consistency but no conclusions could be drawn for the stability of the instrument, the relationships between scales in the instrument, and its ability to detect grade level differences in response patterns.