This posttest-only control group design study provides research on whether electronic-team (e-team) membership stability has an effect on team members' perception of peers' contributions and on learning performance. Team membership was either stable or fluid over the course of the study. The research on collaborative, synchronous e-team learning with stable and fluid teams is limited. Previous research has focused on other characteristics of collaborative e-teams, but e-team membership stability and its postulated effect on team members' contribution had not been examined by an experimental study. The 82 subjects were undergraduate education students at a private, intermountain west university, enrolled in a face-to-face (F2F) literacy class. The class required four small-group, collaborative, hour-long learning sessions during which the e-teams met virtually, completed group projects, and rated their peers' contributions. Subjects were randomly assigned to e-teams whose membership changed each of the four sessions (fluid) or remained the same (stable). There were 12 fluid teams, and eight stable teams of 3-4 members each. Subjects rated their fellow e-team members' contribution to the session after each meeting. Each e-team also submitted a team project after each session. A repeated measures ANOVA tested whether or not there was a statistically significant difference in perceived peer contributions and learning performance between stable and fluid e-teams. The results indicated there was a significant difference between stable and fluid e-teams based on perceived peer contributions over the four sessions, with stable e-team members scoring their peers' contributions higher over time. There was a weak correlation between the e-teams' performance scores and perceived peer contribution scores; however, there was no difference in performance based on the fluid or stable team condition. In addition, the number of students perceived as Social Loafers or Free Riders (making little or no contribution to the group) consistently decreased over the four sessions for the stable teams, but varied from session to session for fluid teams. It is concluded that, while fluid and stable e-teams may be equally effective in terms of student performance, stable e-teams produced higher perceived peer contribution ratings and lower social loafer/free rider ratings over time than fluid e-teams. Future research on the effects of e-team stability in other educational and working contexts is suggested. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]