O'Connor, MartinMartinO'Connor2022-11-072022-11-072022 the A2022http://hdl.handle.net/10197/13238The promotion of positive psychological functioning is a major public health need and a key objective of clinical psychology. Cognitive and behavioural processes hold promise as means to this end, and process-based CBT provides a coherent system for their integration. The research programme described in this thesis investigated the promotion of positive functioning through such processes. Accordingly, three studies are reported and each explored the promotion of positive functioning through cognitive and behavioural processes. Study 1 focused on facilitating the application of processes to conceptualise cases in process-based CBT by evaluating a conceptual model. This model proposed resilience as a pathway through which transtherapeutic mindfulness processes promote positive mental health. Findings from this study provided empirical support for the model in a sample of 129 early adolescents. This publication helped lay a conceptual foundation for the subsequent studies in this research programme. Study 2 aimed to advance the process-based CBT agenda of distilling the literature on processes that promote of positive psychological functioning. In accordance, a systematic review and meta-analysis was conducted to elucidate the efficacy of mindfulness process in promoting resilience. The findings of 57 randomised controlled trials were synthesised and revealed that mindfulness processes are efficacious in promoting resilience, but not more so than comparison interventions. This set of findings provided an empirical basis for Study 3. Study 3 sought to extend the nascent empirical research on process-based CBT interventions. A cluster randomised controlled trial was conducted to evaluate the efficacy of an intervention which integrated the processes explored in the two preceding studies. Findings did not support the efficacy of this intervention in enhancing positive psychological functioning outcomes in a sample of 604 early adolescents. Collectively, the three studies contribute to the scientific literature and present a number of implications for the practice of clinical psychology.enMindfulnessResiliencePositive mental healthProcess-based CBTDoctoral Thesis2022-10-28https://creativecommons.org/licenses/by-nc-nd/3.0/ie/