Research has a critical role in supporting the implementation of farming practices that are appropriate for meeting food and climate security for a growing global population. Notwithstanding progress towards more sustainable agricultural production, the rate of change varies across and within regions and is, overall, too slow. Understanding what is and is not working at the implementation level and, critically, providing justified explanations on outcomes, is an important contribution of the literature. Based on the assumption that theory-informed research can contribute to adoption policy and practice, this review ascertained and described the use of theory in the identification and examination of barriers to adoption in studies included in a recent systematic literature review. Following the application of criteria for ‘theory use’, 16 studies out of 75 were found to have applied or built upon one or more of 14 theories and models in their research approaches, including established theories in the social and behavioural sciences, as well as systems based models developed specifically in the sustainable agriculture space. Following a description of theory and model use in the studies, results are discussed relative to how theoretical constructs and mechanisms within individual and across studies can assist in explaining why and how adoption of sustainable practices is constrained.