This study examined how individual teachers responded differently to professional collaboration aimed at improving instruction for students with disabilities. The researchers found that some teachers readily adopted and implemented strategies learned in collaboration, while others did not. Teachers varied in their knowledge of curriculum, pedagogy, student management, and student-centered instruction. Those who were better able to reflect on and adapt their instruction profited more from collaboration. The study suggests teacher qualities like knowledge and beliefs influence how much they learn from collaborative opportunities. Understanding these differences could help improve collaborative professional development.