From the 1980s onwards pharmaceutical manufacture evolved from a fragmented industry to a global oligopoly. In the ecology literature coevolution theory proposes that V competing species (incumbent firms) interact and shape each others’ development, and V that this in turn potentially shapes the community (industry) structure. This suggests that when exploring how firms’ strategies changed during a period of significant industry change it is important to understand processes of both strategy evolution and coevolution in order to understand the dynamics of strategic change. This led to the research question ‘How did the realised strategies of a heterogeneous set of firms coevolve during the period of pharmaceutical industry consolidation from 1992-2002?’ In order to answer this a categorisation of strategic actions realised by firms in the pharmaceutical industry was developed. This was used as the basis of a methodological framework which used qualitative document analysis to longitudinally analyse how the grand strategies and strategic actions of a set of six pharmaceutical firms evolved and coevolved. These firms had arrived at different strategic outcomes and were selected using purposive sampling and replication logic. For the period 1992-2002 it was found that each firm realised unique patterns of grand strategy evolution. Further, the strategic actions that formed realised strategies coevolved both with the strategic actions of other firms and with the structure of the pharmaceutical industry as it became increasingly consolidated and globalised. Contributions to theories surrounding the environmental determinism versus strategic choice debate have been made with the findings supporting theories of coevolution, incremental and emergent strategy, and temporal patterns in strategy development. New contributions to knowledge were the development of a theory of pharmaceutical industry coevolution, development of a methodological framework for understanding strategic change in the pharmaceutical industry, and the creation of techniques to aid strategic decision making