Teacher absenteeism is one of the most troubling obstacles on the path toward universal access to learning opportunities at school. Over the past decades, studies have found that teacher absenteeism is particularly prevalent in certain parts of Africa. While Guinea-Bissau has not administered or taken part in regional or international efforts to systematically monitor and assess the rates of teacher absenteeism, the issue is noted in the 2017-2025 Education Sector Plan, which includes an aim to strengthen controls on teacher absenteeism. This Time to Teach study seeks to fill this important knowledge gap and support the Ministry of National Education and Higher Education in its efforts to strengthen the teachers' role in school to increase their time on task. This study outlines the various forms of primary school teacher absenteeism (e.g., absence from school, classroom, teaching, etc.), explores teacher absenteeism from a systemic perspective and identifies factors at different levels of the education system that affect teacher attendance and time on task. It also identifies gaps in teacher policy and policy implementation linked to identified determinants of absenteeism and barriers to higher teacher attendance rates, and identifies promising practices and actionable policy recommendations on increasing teachers' time on task.