It is not known how emotion regulation deficits and strategies may differentially relate to nonsuicidal self-injury (NSSI) and suicide ideation in samples of community-based adolescents. The current study examined emotion regulation using comprehensive multi-method assessment to identify which specific deficits are uniquely related to NSSI and suicide ideation in a sample of high school students. Regarding specific deficits, it was expected that lack of emotional awareness, lack of access to emotion regulation strategies, poor cognitive reappraisal, and poorer automatic emotion processing would uniquely associate with past-year NSSI engagement. It was also predicted that lack of access to strategies, lack of impulse control, lack of awareness, and nonacceptance of emotion would uniquely associate with past-year presence of suicide ideation and suicide ideation severity. The sample included 696 adolescents (54.8% female; ages 14-17; mean age = 15.5) recruited from public high schools. Self-report measures were administered assessing suicide ideation, NSSI engagement, dimensions of emotion regulation, and automatic emotion processing (Emotion Stroop). Emotion suppression was the only unique and significant predictor of past-year NSSI engagement, and lack of access to emotion regulation strategies was the strongest predictor of both past-year presence of suicide ideation and recent suicide ideation severity when accounting for all deficits in the same model. Acquiring emotion regulation skills during the period of adolescence has great potential to buffer from occurrence of NSSI and severity of suicide ideation.