Complexity theory, including non-linear dynamics, provides a powerful approach to
understanding and analysing complex interactions as seen when group members learn and
develop. However, complexity theory does not feature heavily in the coaching literature,
depriving coaches of this tool. This paper discusses the implications of non-linear dynamics on
our understanding of group development and illustrate this with a toy model of anger in a
group of three. While formal mathematical modelling of group behaviour is probably not
achievable, the insights can help coaches understand how best to intervene to maximise their
impact and bring benefit to their clients