Objectives: Physical education (PE) plays an important role in contributing to students' physical activity (PA); however, moderate-to-vigorous PA (MVPA) within PE is lower than recommended. Little is known about the PA levels of students from disadvantaged schools within PE. This study aimed to describe: (i) the PA levels of students from disadvantaged secondary schools during PE lessons, (ii) the lesson context and teacher interactions occurring during PE, and (iii) the associations between teacher, school or PE lesson characteristics with student physical activity levels in PE.: Design: Cross-sectional study of 100 Grade 7 PE lessons across 10 secondary schools.: Methods: System for observing fitness instruction time (SOFIT) was used to assess student PA, lesson context, and teacher interaction. Teacher and school characteristics were collected via survey. Mean proportion of lesson time was used to describe PA, lesson context and teacher interaction. Associations between each outcome variable and each characteristic were examined using 2-sample t-tests, ANOVAs and linear regression.: Results: Thirty-nine percent of PE lesson was spent in MVPA, and less than 10% spent in VA. Lessons in schools in urban areas included significantly more MVPA than rural areas (P = 0.04). Male teachers and more experienced teachers conducted lessons with significantly more VA than female and less experienced teachers (P = 0.04 and 0.02). MVPA was also higher in lessons conducted by more experienced teachers.: Conclusion: PA during PE lessons within disadvantaged secondary schools is below international recommendations. Male teachers, more experienced teachers and schools in urban regions teach more active lessons.