The benefits of mixed methods are well recognised. Using mixed methods, researchers are able to overcome shortcomings inherent in individual methods while enhancing the validity and reliability of their research findings. Mixed methods are commonly used in cross-sectional studies – to answer research questions, and/or explore contemporary social issues. However, when researchers are interested in understanding cause and effect relationships that happened over a long period of time, Comparative-Historical Analysis (CHA), which is longitudinal by nature, can be used in combination with mixed methods to understand the causal mechanism of a series of events, and generalise the research findings. Using a case study that involves technology transfer with the rice farmers in the Mekong delta of Vietnam, we describe how CHA could be used in conjunction with mixed methods to better understand why the decade-long mutual aid farming practice among rice farmers in the Mekong delta was abandoned after more than fifty years’ existence. We recommend the use of CHA in conjunction with cross-sectional methods for similar social contexts, and suggest future research that aims to understand cooperative behaviours in farm settings.