The aim of this study was to examine the secular trends in fundamental movement skills (FMS) among 15- to 16-year-old adolescents at 2 assessment points scheduled in 2003 and 2010 and to investigate the associations between FMS, physical activity (PA), and body mass index (BMI). In 2003, self-reported PA, weight and height, and objective FMS scores were collected from 2390 students, and in 2010, similar data were generated from a second sample of 1346 students. FMS were assessed during both assessment phases using 3 identical objective FMS tests that were figure 8 dribbling, jumping laterally, and coordination track tests. This study indicated that the sum index of FMS did not change among the boys and the girls between 2 data collection points. However, findings demonstrated a secular decline in coordination test scores in both gender groups between 2 measurement points but an improvement in girls’ object control skills between 2003 and 2010. The results also showed that FMS had a significant main effect on BMI in both gender groups, whereas the main effect of PA on BMI was not significant for either gender group. Results also demonstrated that there was no significant interaction effect between FMS and PA on BMI in either of the girls’ or the boys’ groups.