The objective of this chapter is to explore the characteristics of the diary research method and its use in a social marketing context. First, the diary research method is discussed and presented, including justification for use, definitions, classifications, typologies, methods of recording data, and contexts for use. The chapter presents one case study featuring use of paper-and-pencil consumer diaries combined with focus group interviews, in the context of alcohol consumption. The advantages and disadvantages of using the consumer diary research method in social marketing are also presented. The practical case study identifies key benefits for using consumer diaries in social marketing research including information gathering and reflexivity of diarists.