Additional Study Information: This NIH-funded research study uses brain imaging to explore the biological causes of major depression and suicide. We hope to develop a better understanding of how people who feel depressed and suicidal cope with their feelings so we can improve treatment and prevention. You may qualify if you have depression with or without suicidal thoughts or previous suicide attempts. Participation involves a set of diagnostic interviews, brain imaging scans (MRI and PET) and neuropsychological tasks. Eligible individuals will be compensated up to $750 and may receive up to 3 months of free doctor visits for medication treatment. If you also sign up for our companion behavioral study, you could receive up to $1,250. Our rigorous safety protocols minimize the risk of COVID-19 exposure