Most students arrive at game-focused physical education (PE) with neither the skills nor the tactical knowledge to be successful (Metzler, 2000). Although the Teaching Games for Understanding (TGFU) approach can enhance both on- and off-the-ball skills in game play performance (Griffin et al., 1995; Harvey et al., in review, Harvey 2003; Mitchell et al., 1995) results from previous research examining TGFU's effectiveness in PE settings have been equivocal. The present study was conducted to assess whether an 11-13 lesson unit of soccer taught using the TGFU approach could improve the Game Performance (GP) of grade six physical education students (ages 11-12), across skill levels, and class periods. Three students (a higher-, moderate- and lower-skilled student) were randomly selected as the unit of analysis from four different grade six PE classes (n=12). Students were followed over an 11-13 soccer unit taught using the TGFU approach. Data were collected on eight measures of GP using the Game Performance Assessment Instrument (GPAI). Elements of GP were formulated into four GP indices: Decision Making Index (DMI); Skill Execution Index (SEI); overall GP Index (GPI); and Game Involvement (GI). The GI Index was divided further into appropriate/inappropriate on- and off-the-ball actions. All GP data were plotted graphically and analyzed using standard visual analysis tactics. All GP indices and GI remained somewhat variable between the baseline and intervention phases of the study and no individual participants improved on all GP and/or GI indices. However, 10 of the 12 participants improved at least one aspect of their GP, with seven improving their SEI, four their DMI and six their GPI when compared to baseline. Furthermore, nine of the 12 participants increased either their appropriate GI or decreased their inappropriate GI when compared to baseline, with 10 of the 12 participants improving their on-the-ball GI and five of 12 their off-the-ball GI when compared to baseline. Results also showed that two of the moderate skilled girls had significantly lower on-the-ball involvement than the other participants in the study. Finally, participants in the classes who had both fewer participants and fewer teaching sessions performed better on their GP indices when compared to baseline. A TGFU-based unit of soccer, focused on teaching both on and off-the-ball elements of game play, is associated with developments in participants' GP and GI indices across participants from high, moderate and low skill levels, especially those in class periods with fewer teaching sessions and participants.Keyword(s): assessment, middle school issues, physical education PK-12