Background: This study examines the national prevalence rates of suicidal ideation and attempts among adults with and without major depressive episode (MDE) in five demographic groups –race, sex, age, education, and marital status – in the United States. Methods: Data extracted from the 2018 National Survey on Drug Use and Health (NSDUH) were analyzed , producing 42,551 records. Wald chi-square diagnostic examination was conducted on the multinomial logistic regression (MLR) model with five demographic predictor variables. Results: The highest rates of suicidal ideation for those with MDE occurred in White females (40.6%), adults 18-25 years old (36.4%), individuals with some college education (40.4%), and unmarried adults (57.1%). For those without MDE, the highest rates of suicidal ideation occurred among White males (31.9%), adults 18-25 years old (31.9%), individuals with some college education (38.7%), and unmarried adults (49.6%). Among the same demographic groups, proportions of suicide attempts were highest for those with MDE. A chi-square test indicated significant differences across adults with and without MDE in all demographic groups. The MLR model fitting results showed that the five demographic variables were significant predictors of suicidal ideation and attempts in both populations (p<0.05). Limitations: Our data are cross-sectional and no directionality or causality can be assumed between study variables. A small proportion of the population was excluded from the survey. Conclusions: serious mental health needs are unmet for many demographic groups, especially among individuals with depression. Population-based clinical interventions are needed to reduce rates of depression, suicidal ideation, and attempts.