Low socioeconomic status (SES) has been associated with distinct patterns of reward processing, which appear to have adverse implications for health outcomes, well-being, and human capital. However, most studies in this literature have used complex tasks that engage more than reward processing and/or retrospectively studied childhood SES in samples of adults. To clarify how SES relates to the development of reward processing tendencies, we measured income-to-poverty ratio (IPR) in 172 youth who subsequently underwent functional MRI while completing a passive avoidance task to assess neural responses to reward and loss information. Participants were 12–15 years old (mean = 13.94, SD = .52; 65.7% female) from a sample broadly representative of the Chicago area in terms of SES (IPR range = 0.1–34.53; mean = 3.90; SD = 4.15) and racial makeup (40.1% European-American; 30.8% Black; 29.1% Hispanic). To the extent they had lower IPR, children displayed a trend toward worse behavioral performance on the passive avoidance task. Lower IPR also was associated with a greater response in attention brain regions to reward and loss cues and to reward and loss feedback. Lower IPR also was associated with reduced differentiation between reward and loss feedback in the ventromedial prefrontal and parietal cortex. The current data suggest that both increased salience of reward/loss information and reduced discrimination between reward and loss feedback could be factors linking SES with the development of human capital and health outcomes.