This study examines how acquired capability for suicide, negative urgency, and social support effectuate a suicide attempt. Sixty-three adults having visited an emergency room due to a suicide attempt were studied. The results can be summarized as follows. First, there were no significant sex differences in acquired capability for suicide, negative urgency, and social support. Second, the correlation among suicidal ideation, acquired capability for suicide, negative urgency, social support, and suicide attempts was examined. Results showed that suicide attempts were significantly and positively correlated with suicide ideation, acquired capability for suicide, and negative urgency. However, social support and suicide attempts did not significantly correlate. Third, results of hierarchical regression analysis indicated that acquired capability for suicide and negative urgency significantly predicted suicide attempts even when suicide ideation was controlled, but social support did not significantly explain attempts. In other words, study results imply that suicide attempts increase when acquired capability for suicide and negative urgency are high. Study results offer empirical data for understanding the intrinsic characteristics of individuals attempting suicide.