Objective: Two small studies have suggested that family carers of people with dementia may be a high-risk group for suicide. The objective of this study was to further explore the rate of suicidal ideation in a large sample of carers and identify psychosocial risk and protective factors. Method: A cross-sectional survey was conducted with 566 family carers. The survey included measures of suicidality, self-efficacy, physical health, depression, anxiety, hopelessness, optimism, burden, coping strategies, and social support. Results: Sixteen percent of carers had contemplated suicide more than once in the previous year. There were univariate differences between suicidal and non-suicidal carers on self-efficacy, social support, coping, burden, depression, anxiety, hopelessness, optimism, reasons for living, and symptoms of dementia, as well as age and income management. In a multivariate model, age, depression, and reasons for living predicted suicidal ideation. In tests for mediation, satisfaction with social support and dysfunctional coping had indirect effects on suicidal ideation via depression. Conclusion: Family carers of people with dementia have high rates of suicidal ideation, with depression a risk factor and increasing age and reasons for living as protective factors. Depression and reasons for living should be targeted in interventions to reduce suicide risk in dementia carers.