This paper uses Danish register-based matched student–teacher data to characterize public school teachers and their working conditions. We document gender segregation across subjects and grades, with female teachers dominating Danish instruction and male teachers more common in upper-grade math. Teachers select into subjects based on subject-specific academic skills, yet a notable share has weak prerequisite skills. Teachers often specialize in student age groups but teach multiple subjects. Those with stronger skills tend to work in schools with similarly skilled colleagues. These findings provide new insights relevant for interpreting education research and designing policies to improve teacher retention and wellbeing.