AbstractThe study, carried out in a large laboratory, shows that performance increases up to 1. 5 years tenure, stays steady for a time but by five years has declined noticeably. This tendency is best accounted for by the marked decline in communication rate among group members and between them and critical external sources of information. The authors analyse the significance of this finding and suggest means of maintaining the vitality of long‐standing project teams.The study, carried out in a large laboratory, shows that performance increases up to 1. 5 years tenure, stays steady for a time but by five years has declined noticeably. This tendency is best accounted for by the marked decline in communication rate among group members and between them and critical external sources of information. The authors analyse the significance of this finding and suggest means of maintaining the vitality of long‐standing project te