Purpose: There is evidence that social isolation is a risk factor for suicide, and that social connections are protective. Only a limited number of studies have attempted to correlate the number of social connections a person has in their life and suicidal behaviour. Method: Two population-based case–control studies of young adults (18–34 years) were conducted in New South Wales, Australia. Cases included both suicides (n=84) and attempts (n=101). Living controls selected from the general population were matched to cases by age-group and sex. Social connections was the main exposure variable (representing the number of connections a person had in their life). Suicide and attempts as outcomes were modelled separately and in combination using conditional logistic regression modelling. The analysis was adjusted for marital status, socio-economic status, and diagnosis of an affective or anxiety disorder. Results: Following adjustment for other variables, those who had 3–4 social connections had 74% lower odds of suicide deaths or attempts (OR=0.26, 95% CI 0.08, 0.84, p=0.025), and those with 5–6 connections had 89% lower odds of suicide deaths or attempts (OR=0.11 95% CI 0.03, 0.35, p