Background: Childhood neglect is a risk factor for subsequent mental health problems. However, research on the unique contribution of emotional and physical subtypes of neglect is lacking. Importantly, if emotional and physical neglect have different impacts on mental health, they must be examined separately to understand how to prevent and treat their effects. Objective: This study aimed to examine associations of emotional and physical neglect with depression, anxiety, stress, alcohol and drug use in 18- to 20-year-olds. Methods: Participants ( N = 569, mean age = 18.9, 70% female) responded in an online survey to questions on childhood emotional and physical neglect, childhood abuse, symptoms of depression, anxiety and stress, and alcohol and drug use and problems. Procedures were approved by the University of Sydney Human Ethics Committee. Hierarchical linear regressions were performed, controlling for socio-demographic characteristics and other adverse childhood experiences. Results: Combined neglect was associated with depression ( B = 2.895, p < 0.001), anxiety ( B = 1.572, p = 0.003) and stress ( B = 1.781, p = 0.001). However, a second model entering emotional and physical neglect as separate exposures revealed emotional neglect was driving this association with depression ( B = 2.884, p < 0.001), anxiety ( B = 1.627, p = 0.001) and stress ( B = 1.776, p = 0.001), and that physical neglect was not associated with any outcome. Neither emotional nor physical neglect were associated with alcohol or drug use. Conclusion: Emotional neglect is a risk factor for mental health problems in early adulthood. Research that combines emotional and physical neglect into a single exposure may be obscuring relationships with mental health. Mental health prevention and treatment must screen for, and address, emotional neglect.