Classroom observation tools can play an important role in teacher candidate evaluation and training. However, the field of special education has not developed observation tools explicitly for teacher candidates, tools that measure constructs important to special education. To help provide teacher candidates with constructive feedback, it is incumbent upon the developers of observation tools to provide evidence that the interpretations of ratings and decisions based on observation scores are accurate and reliable representations of a teacher candidate's instructional practice. This study applied Kane's argument-based framework to evaluate data related to three inferences (scoring, generalization, implications) derived from a small-scale, preliminary validation study of the Preservice Observation Instrument for Special Education (POISE) in an early reading intervention context. Kane's framework was used to specify the proposed interpretations and uses of the POISE scores by creating a network of inferences and assumptions involved in this observation tool and elaborate whether the proposed interpretations and uses have been supported by empirical evidence from the study. The sample included special education teacher candidates (N = 14) and university supervisors (N = 8). The university supervisors were trained on POISE and scored teacher candidates over a minimum of 6 lessons. Supervisors also completed a social validity survey related to POISE's feasibility and usefulness as a formative assessment. Findings from the study show that trained supervisors could distinguish between effective and ineffective teacher candidates' performances in the area of early reading intervention instruction. Additionally, supervisors thought that POISE helps generate constructive feedback and is valuable for improving teacher candidates' teaching. Taken together, POISE contributes to the small collection of available tools in special education by developing scores that may have a practical import that faculty can use to help monitor teacher candidates' progress and facilitate their development. I discuss future research based on key findings from the analyses and survey results, and recommendations for practice. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]