Many adolescent girls do not achieve a health-enhancing level of physical activity. This study aimed to identify the school physical environment factors that adolescent girls perceive to be important and influential regarding their physical education (PE) behaviour. Adolescent girls (n = 38; aged 13–16) participated in eight moderated focus groups, which were audio recorded and transcribed verbatim. The data were inductively content-analysed using NVivo to cluster participants’ comments into hierarchical themes. Six higher order themes emerged relating to the physical environment and included both positive and negative comments. Emergent themes related to 1) the activities offered; 2) the quality of the facilities for PE and changing; 3) the equipment available; 4) the length, quantity and scheduling of PE during the day; and the influence of 5) the weather and 6) clothing on PE participation. From the emergent findings it is evident that the physical environment is perceived as important to girls and can influence the quality of their PE experience. These findings may be used by teachers and exercise leaders to create an environment conducive to enhancing physical activity levels.