Bipolar disorder is characterised by intense fluctuations in mood, including the experience of severe episodes of depression, mania and hypomania. The experience of bipolar disorder can also be associated with biases in various cognitive processes, including rumination in response to positive and negative mood states and tendencies to make dysfunctional self-appraisals. Preliminary research has also suggested that bipolar disorder may be associated with deficits in the recall of specifically detailed autobiographical memories.The lack of specificity in the recall of autobiographical memories, known as the "overgeneral" recall bias, refers to tendencies to generate generalised memory representations as the memory recall process is terminated prior to the activation of specifically detailed memories. This overgeneral recall of autobiographical memories can also contribute to ruminative thought patterns, impair the generation of effective solutions to problems, and is associated with poor illness outcomes. The overgeneral bias has been extensively researched within major depressive disorder and suicidality, but has been comparatively under-researched in bipolar disorder and in vulnerable individuals.A series of eight studies were designed to: (i) investigate the cross-sectional associations across measures of positive and negative rumination and self-appraisal with the vulnerability to hypomania, and investigate the associations of these cognitive styles with prospective mood symptoms in an at-risk sample; (ii) investigate the cognitive vulnerability to hypomania in relation to rumination, problem-solving and autobiographical memory specificity; (iii) conduct a preliminary investigation into the associations between goal-related memory processes and extreme goal-pursuit in relation to hypomania vulnerability; (iv) investigate whether the vulnerability to hypomania and future bipolar disorders is associated with similar patterns of overgeneral memory recall on a standardised cue memory task; and (v) investigate the patterns of autobiographical memory specificity within a remitted bipolar sample. The heightened vulnerability to future bipolar disorders was associated with tendencies to engage in both positive and negative forms of ruminative thought processes, and with poorer psychosocial problem-solving, however, this relationship with problem-solving was not independent of current mood symptoms. The results of two studies indicated that the heightened vulnerability to hypomania was associated with an overgeneral memory bias across two different assessments of memory specificity, in direct contrast to previous research. Individuals diagnosed with bipolar disorder also reported more extreme overgenerality during memory recall than a sample of age and gender-matched healthy controls, but were able to recall some specifically detailed negative memories in short response latencies compared to non-bipolar control participants. The research presented within this thesis supports the notion of a continuum of increasing overgenerality in the bipolar disorder spectrum, inclusive of at-risk individuals to people formally diagnosed with bipolar disorder. Although bipolar disorder appears to be associated with a trait-based overgeneral memory bias, bipolar individuals appear to have ready access to some specific negative memories even during remission from symptoms. The clinical implications of this research, methodological considerations in the assessment of memory specificity, and directions for further investigations into the nature of autobiographical memory recall in bipolar spectrum disorders are discussed.