The present study was designed to examine the etiology of suicidal behavior from cognitive and developmental perspectives. Given empirical evidence suggesting links between early negative life events and suicidal behavior, between early negative life events and cognitive factors, and between cognitive factors and suicidal behavior, it was hypothesized that early negative life events may impact individuals' suicidal behavior by affecting these individuals' cognitive functioning. That is, cognitive functioning may serve as a mediator in the relationship between early life events and suicidal behavior. The present study examined child maltreatment, family instability, and poor general family environment as early negative life events, and examined self-esteem, locus of control, hopelessness, and problem-solving deficits as cognitive factors. In addition, individuals' perceived social support before age 18 and current social support and life stress were also examined in relation to the above variables. The subject sample was comprised of 181 college students, including 51 suicidal, 60 depressed, and 70 normal-control individuals. Results from the study indicated that these three groups could be discriminated at highly satisfactory levels by using the above variables. A series of structural equation analyses also indicated that, even though early negative life events have mild direct impact on suicidal behavior, these events seem to have stronger direct impact on cognitive deficits which in turn seem to have stronger direct impact on suicidal behavior. / Ph. D.