SHAPE America has highlighted the importance of developing physically literate children as part of quality physical education programming. Unfortunately, most children know little about physical activity and health-related fitness. The purpose of this study was to examine the physical activity and fitness content knowledge of at-risk inner-city children and determine if students who accumulate more physical activity, do more PACER laps, and/or have a lower BMI have higher levels of knowledge. Participants included 569 inner-city children (300 girls, 269 boys) from the Southwest USA who completed the PE Metrics knowledge test, wore a pedometer for 1 school week, completed the PACER test, and had their height and weight measured. Two-way and three-way factorial ANOVA tests were used to examine potential differences between genders, between grades, and among tertiles of physical activity and health-related fitness performance on the PE Metrics knowledge test. On average, students scored 38% on the PE Metrics knowledge test. Boys and girls scored similarly, sixth graders scored lower than fourth and fifth graders, and children who were in the low and high BMI tertiles scored higher than children in the medium tertile (p < 0.05). As school day step counts and PACER laps increased, knowledge scores trended higher. At-risk youth need additional opportunities to learn content knowledge related to physical activity and fitness. Increased physical activity and aerobic fitness were related to small increases in knowledge scores. Future interventions should focus on child behavior and knowledge.