There is an emphasis on developing partnerships throughout the Department of Health and other Government departments. Health Action Zones (HAZs) highlight the need for flexible working across boundaries at a local level. How to evaluate these partnerships in a manner that is practicable, pragmatic, straightforward for researchers and non-researchers alike is an issue that needs to be addressed. This paper assesses the potential of a community based evaluation tool – the Theories of Change Model – as an approach to evaluating partnerships. The model was applied to a very focused partnership between the Nottingham HAZ Evaluation Manager and the Local Co-ordinator of Trent Focus (an organisation funded by the NHSE Trent, to promote research and development in primary care). The aim was to provide an opportunity to portray the usefulness and limitations of implementing a theory based approach to ‘valuing’ primary care partnership working at a local level. The evaluation process itself was an important element of the formulation and implementation of the partnership. It helped to decide the aims and objectives of the partnership and proposed a theory as to why the partnership was worth investing in. At a minimum, if applied at the inception of a new partnership, the model was seen as a very useful planning tool. The process was very time consuming and to be most effective, needed the commitment from all key stakeholders involved in the partnership. This paper is an attempt to provide researchers/evaluators, in the widest sense, with a possible framework that would allow organizations to acknowledge, justify and address complex partnership working for health gain. This paper is of importance to anyone interested in defining and measuring desired processes and outcomes from partnership working.