The current thinking about the suicide attempt process in suicidology contains a long-held assumption that the change from thoughts to behaviours can occur either impulsively or non-impulsively and classification of suicide attempts into groups according to impulsivity is a tradition that has existed for more than a hundred years (e.g., Durkheim, 1897/2006). However, a systematic review of the literature on suicide attempt impulsivity, presented in the thesis, indicated that, despite differences between impulsive and non-impulsive suicide having been extensively studied, the results are difficult to integrate and to translate into recommendations for suicide risk assessment and prevention. The thesis sought to advance current understanding of suicide attempt impulsivity and examine whether there is a phenomenon that warrants description as an impulsive suicide attempt. The empirical research in this thesis includes two studies. The first is a small-scale qualitative study which used thematic analysis to explore the ways clinicians (n = 7) and suicide attempters (n = 8) themselves understand suicide attempt impulsivity. It was based in an outpatient mental health clinic specialising in the treatment of suicidal behaviour. Although the concept of attempt impulsivity originated from clinical work and continues to be used in that setting, there has been very little exploration of how the concept “impulsive attempt” is used. The small scale qualitative study thus provides an important exploration of alternative definitions of suicide attempt impulsivity. The study showed that three themes, “thinking out”, build-up, and unclear intentionality were used by clinicians and suicide attempters when considering attempt impulsivity. However, the study indicated limitations of the term in clinical practice, such as potential stigmatisation and limited contribution to suicide risk assessment.