Multiple team membership as a work design feature is becoming more widespread in modern organizations, with expected positive and negative consequences for individual employees. This study explores whether fragmentation of time across multiple teams is a job demand or a job resource for employees. Drawing on the Job Demands–Resources framework and role theory, we tested a model that relates multiple team membership to a set of job demands (task load, team process load, and conflict with team members) and job resources (team social support and job autonomy). The findings show that multiple team membership increased demands associated with teamwork but not taskwork, while simultaneously reducing social support from team members. In turn, job demands increased job strain, whereas job resources increased work engagement. We conclude that the fragmentation of time across different roles in multiple teams is perceived as a teamwork-related job demand and leads to role strain. The theoretical and practical implications of our findings are further discussed.