The Internalizing (INT) and Externalizing (EXT) spectra are an emerging way to conceptualize the structure of psychopathology. Demonstrating relationships with emotional reactions to, and cognitive appraisals of, daily stressful events would be strong evidence of ecological validity. In the current study (N = 78), the experience sampling method (ESM, a structured diary technique with Palm Pilots) was used to capture affect and cognition related to current stressor, five times per day, for 1 week. Multilevel random coefficient modeling was used to examine affective and cognitive reactivity to daily stressors as a function of baseline levels of INT and EXT. INT scores were related to higher levels of negative affect (NA), lower levels of positive affect (PA) and more negative cognitive appraisals of the stressful situation. Several cross-level interactions were found between psychopathology scores, cognitive appraisals, and affect. Participants higher in INT psychopathology showed less decrease in NA as level of control increased, compared to participants low in INT. EXT moderated the association between NA and distress, with higher levels of EXT resulting in a stronger association between distress and NA. INT and EXT also moderated the relationships between the cognitive variables (distress and control, coping and control). Findings support both the utility and validity of the INT and EXT dimensions in understanding different forms of stress-related impairment in emotion and cognition.