Cognitive vulnerabilities, such as a negative self-referential processing bias, have been theorized to play a causal role in the development of depression. Indeed, depression is associated with the endorsement and recall of more negative and fewer positive emotional words (i.e., recall biases) in the self-referential encoding task (SRET). In addition, currently depressed adults and adolescents, compared to healthy controls, show an enhanced late positive potential (LPP), an event-related potential (ERP) component that reflects sustained attentional engagement, during the processing of negative relative to positive words in the SRET. However, it is unclear whether these behavioral and neural measures in the SRET are indicators of risk for depression, or are concomitants of the disorder. The present study included 121 8 to 14 year-old girls with no lifetime history of depression, and examined the association between maternal history of depression (i.e., risk) and both behavioral and ERP measures while viewing positive and negative adjectives during the SRET. Lifetime history of major depressive disorder and/or dysthymia in the biological mother was assessed via a semistructured diagnostic interview. Results indicated that participants with maternal history of depression, compared with those with no maternal history of depression, demonstrated an enhanced LPP to negative words. There were no group differences in the LPP to positive words. Maternal history of depression was also related to faster response time when rejecting negative words. Participant’s current depression symptoms were associated with increased negative recall bias and decreased positive recall bias. The present study provides novel evidence that abnormal electrocortical reactivity to negative self-referential words indexes vulnerability for depression in 8 to 14 year-old girls.