(1) Background: Realist evaluation is a promising approach for evaluating organisational interventions. Crucial to realist evaluation is the development and testing of middle range theories (MRTs). MRTs are programme theories that outline how the intervention mechanisms work in a specific context to bring about certain outcomes. To the best of our knowledge, no organisational intervention study has yet developed initial MRTs. This study aimed to develop initial MRTs based on qualitative evidence from the development phase of an organisational intervention in a large multi-national organisation, the US food service industry. (2) Methods: Data were collected through 20 semi-structured interviews with the organisation's managers, five focus groups with a total of 30 employees, and five worksite observations. Template analysis was used to analyse data. (3) Results: Four initial MRTs were developed based on four mechanisms of participation, leadership commitment, communication, and tailoring the intervention to fit the organisational context to formulate 'what may work for whom in which circumstances?' in organisational interventions; (4) Conclusions: Our findings provide insights into 'how' and 'which' initial MRTs can be developed in organisational interventions.
Keywords: context–mechanism–outcome configuration; mechanism; middle range theory; organisational interventions; realist evaluation.