Objective: The aim of this study was to evaluate whether a shortened-length session of CogMed Working Memory Training (CWMT) would be a suitable active control group and evaluate study protocol to aid in design refinements for a larger randomized controlled trial (RCT). Method: Thirty-eight post-secondary students diagnosed with ADHD were randomized into 25 sessions of standard (45 min/session) or shortened (15 min/session) CWMT, or into a waitlist control group. Results: There was no significant difference in completion rate or training index score between the standard- and shortened-length groups indicating that both groups showed improvement and put forth good effort during training. Conclusion: Preliminary findings suggest that shorter training sessions may induce similar levels of engagement, motivation, and expectancy of improvement in participants. We conclude that a larger scale RCT that utilizes shortened-length training as an active control group is warranted, but that a few modifications to the study protocol will be required.