Thesis by publication."Centre for Emotional Health, Department of Psychology, Faculty of Human Sciences, Macquarie University" -- title page.Includes bibliographical references.Chapter One. General introduction -- Chapter Two. Study One. The role of dispositional mindfulness in affective and physiological reactivity across the adult lifespan : a systematic review -- Chapter Three. Study Two. Affective and physiological reactivity across adulthood : the role of dispositional mindfulness -- Chapter Four. General discussion.Ageing is associated with a number of changes, including an increase in positive affect (Stawski, Sliwinski, Almeida, & Smyth, 2008), reduction in negative affect (Kessler & Staudinger, 2009), and overall enhanced emotion regulation (Gross et al., 1997). One factor that may contribute to these age-related changes is mindfulness, defined as an awareness of and attention to the present moment (Brown & Ryan, 2003). The first paper reviewed the literature regarding dispositional mindfulness, and affective and physiological reactivity across the adult lifespan, and identified a paucity of relevant studies. The second paper investigated the role of dispositional mindfulness on physiological and affect reactivity, using a sample of younger, middle-aged and older adults who completed two mood-induction tasks. A significant correlation was found between dispositional mindfulness and age. Furthermore, older adults reported higher levels of positive affect, and lower levels of negative affect and perceived stress, compared to middle-aged and younger adults. No significant differences were identified in physiological reactivity by age. Finally, dispositional mindfulness was found to be related to positive affect. The findings from the present thesis will contribute to our knowledge of the relationship between dispositional mindfulness, affective and physiological reactivity, and ageing.Mode of access: World wide web1 online resource (x, 169 pages) graphs, table