Milestone achievements are reduced in people with schizophrenia and are lower in comparison to people with bipolar disorder. However, it is not clear what the implications are for engagement in momentary activities based on milestone achievements. Further, some recent research has suggested that psychotic symptoms are associated with challenges in self-assessment of activities, but there is less information about the correlations of milestone achievements and ongoing psychotic symptoms. We examined momentary activities and symptoms as a function of lifetime milestone achievement in 102 individuals with schizophrenia and 71 with bipolar disorder. Ecological Momentary Assessment (EMA) was used to sample daily activities and concurrent symptoms 3 times per day for 30 days. Each survey asked the participant where they were, who they were with, and what they were doing, as well as sampling the concurrent presence of psychotic symptoms. Not being financially responsible for their residence was associated with engaging in fewer productive activities. Participants who never had a relationship were more commonly home and alone and engaged in fewer social interactions. A lifetime history of employment was correlated with engaging in more productive activities, including at home. More common momentary psychosis was seen in participants who failed to achieve each of the functional milestones. Lifetime milestone achievements were associated with greater frequencies of productive behaviors and with fewer momentary experiences of psychosis, suggesting that psychotic symptoms may have importance for sustaining disability that would be challenging to detect without momentary information.