Tuckman's stages of team development

Tuckman proposed that small groups pass through a predictable developmental sequence, running in parallel across two realms — interpersonal and task. The mnemonic stage names are forming, storming, norming and performing; adjourning was added in 1977.

Honestly about the basis, and it differs sharply from the model's fame. The 1965 text is a literature review — Tuckman synthesised 50 articles on group development and induced a common sequence from other authors' descriptions. He ran no experiment, tested no hypothesis and collected no data of his own. The groups reviewed were also mostly therapy and training (T-)groups rather than work or student project teams — the transfer to modern teams was made by later practitioners, not by the 1965 paper.

The most telling datapoint comes from the authors themselves: in the 1977 review, of 22 studies examined only ONE had set out to test the hypothesis directly, and the paper closed by calling for more empirical work.

There is also a direct empirical contradiction: Gersick (1988, Academy of Management Journal, 31(1), 9–41), studying eight naturally occurring task groups, found they did not follow a uniform stage sequence but a "punctuated equilibrium" pattern — long stretches of inertia broken by concentrated change triggered by awareness of deadlines rather than by completing a stage. Bonebright's historical review (2010) describes how the model became popular among practitioners precisely because applied research was lacking. We found no meta-analysis establishing the sequence.

So gslk uses Tuckman only as vocabulary for normalising friction, and never as a diagnosis. There is no licensing question here: the model is freely citable and no official Tuckman instrument exists.