The current emphasis on data-based decision-making ties discussions of accountability, school improvement and educational reform to the notion that gathering and using evidence addresses questions of rigor in our schools and classrooms. The purpose of this research was to survey secondary (middle and high school) general educators (n = 126) to determine which assessments and tools they used most frequently and the types of classroom and student-specific instructional decisions they made from those assessments, particularly for students with disabilities. In addition, comparisons were made to determine if responses differed for general educators engaged in co-teaching. Results indicated that assessments used most frequently were teacher-created tests, entrance/exit slips and questioning techniques. Teachers reported using those assessments and tools for checking for understanding and verifying whether students were retaining the material. Further, those who engaged in co-teaching reported feeling more effective in using data to design and individualize instruction and make adaptations for students with disabilities.