Two investigations aimed to document motivation gains and losses (the Köhler effect and social-loafing effects) in real-life group work. Specifically, using archival data, motivation changes were analyzed from individual to additive group competition in collegiate swim, and high school track and field relays. Results showed that inferior group members had significantly greater motivation gains than noninferior teammates in preliminary and final swim races. Motivation gains also were significantly higher in the final compared to the preliminary race. Similar results were replicated with the track and field athletes with the weakest member of the team showing larger difference scores from individual to group competition compared to middle-ranked and higher-ranked teammates. On the whole, both studies provide ecological support for the Köhler effect, and that inferior team members showed the greatest motivation gains. No significant differences were found to support social-loafing effects within the same groups, but performances of superior group members tended to be slower.