Reading and writing instruction involve teachers guiding students to take on the actions and thinking processes of readers and writers. Think-alouds and write-alouds are research-supported strategies that promote student growth and achievement. Although professional development strategies are outlined in the research literature on using think-alouds for reading and writing instruction, an observation tool that could be used to support teacher reflection and growth was not previously available. Through a developmental, validation process, we created the Think-Aloud Observation Protocol for both reading and writing instruction that has been tested for classroom observations of both in-service and pre-service teachers and follows the rigorous American Education Research Association's (AERA) Standards for Educational and Psychological Testing. The Think-Aloud Observation Protocol supports a reflective stance so that teachers could determine specific ways to improve their use of think-alouds in literacy instruction.