Suicidal behaviours are complex and multifaceted, resulting from a wide range of interacting genetic, psychological, psychiatric, social, economic, and cultural risk factors. The aim of this current study was to explore trajectories of individuals experiencing suicidal ideation and/or suicide attempts, compared to those who do not experience these behaviours. Furthermore, this study aimed to provide up-to-date knowledge of both the predictors and outcomes of suicide behaviours, drawing on data from the Christchurch Health and Development Study. Participants consisted of a New Zealand birth cohort of 1265 individuals, with measures obtained at multiple timepoints up to 40 years of age. Across the lifespan, the prevalence of suicidal ideation ranged from 1.8-9.5%, and suicide plans/attempts ranged from 2.2%-3%. Six childhood factors predicted latent trajectory classes of suicidal behaviours: parental care, peer attitudes, sexual abuse, novelty seeking, parental illegal drug use, and ethnicity. Latent trajectory membership strongly predicted other mental health outcomes in adulthood: depression, anxiety, nicotine-use disorder, alcohol-use disorder, and shorter intimate/significant relationships. This research adds to the current body of literature on suicidal behaviours, allowing for greater understanding of the factors that may enhance an individual’s risk of engagement in these behaviours.