The use of linguistics within market research is for the most part, marked by its absence. This is perhaps surprising given the potential it offers for analysing what people have said and what they might mean. Though the study of 'evaluation' has been approached from many different linguistic perspectives, previous work in this field has tended to focus on individual markers, rather than aiming to provide a fuller, more comprehensive account. This thesis proposes that it is possible to combine approaches from Discourse and Conversation Analysis, with developments in the field of Systemic Functional Grammar, to gain a more inclusive understanding of the social and interactional influences that can determine how an evaluation is both formulated and articulated. The data for this study was collected from thirty paired depth interviews, in the field of New Product Development. This data was transcribed and tagged using O'DOlU1ell's (2007) CorpusTool software. It was then analysed using Martin and White's (2005)framework of Appraisal Theory, in conjunction with a scale developed from Brown and Levinson's (1987) Politeness Theory and Sinclair and Coulthard's (1975, 1992) work on teacher! pupil interactions. As a result of the analysis carried out in this study, two potential extensions to the Appraisal Theory Framework are suggested. These extensions are with regards to the relevance of the subject matter to the speaker making the evaluation, and the notion of neutral evaluations. In addition to taking an existing framework and developing it for a new purpose, this thesis also contributes to the wider understanding of 'evaluation', through the development of a Scale of Importance for individual hu'J1S, with regards to the 'weight' that should be assigned to them due to their place in the turn taking structure.