This study sought to determine the relationship of teacher collaboration and mentoring practices with schools internal efficiency. The study was conducted in 13 public elementary schools in Calauan Sub-Office, Division of Laguna, with 128 teachers. Employing a descriptive-correlational method, the study used a researcher-made, expert-validated survey-questionnaire. Results showed very high extent of individual and team-themed collaboration, alongside mentoring practices show high level across the four evaluated components i.e., motivation, advice, support, and coaching as perceived by the teachers. It was also found that the internal efficiency across all indicators was notably very high suggesting a well-functioning educational environment conducive to academic success and teacher satisfaction. There were varying degrees of association between teacher collaboration and internal efficiency of schools. Most importantly, relationships indicate mentorings many advantages particularly in improving teacher satisfaction, discipline, attendance monitoring, and graduation rates.  Recommendations include structured collaboration sessions, district-wide programs, integrating collaboration into curriculum design, and ongoing professional development. Future research should explore longitudinal collaboration effects and factors influencing collaboration in diverse school contexts.