The main purpose of this dissertation was to highlight and address seven challenges related to the measurement of youth cognition, understanding the role of cognitive constructs in anxiety and... Show moreThe main purpose of this dissertation was to highlight and address seven challenges related to the measurement of youth cognition, understanding the role of cognitive constructs in anxiety and school refusal, and the examination of cognitive mediators of cognitive-behavioural treatment outcomes. The studies presented in this dissertation contributed to the empirically valid assessment of constructs of cognitive processing in youth which were until now only present in cognitive theories of Aron Beck. Now, constructs of cognitive processing coming from the cognitive theories of depression and anxiety of Beck and colleagues can be assessed in youth using one single measure. Further, cognitive dimensions of cognitive products and cognitive processes from Beck and colleagues cognitive theories of emotional disorders were found to be important in the etiology of school refusal. The belief that positive treatment outcomes can be achieved through changes in cognition received support. Using innovative statistical approaches to mediation, it was found that enhanced levels of self-efficacy following cognitive-behavioural treatment for school refusal were associated with increased levels of school attendance and decreased levels of school fear. Show less