While dispositional mindfulness is a popular construct in psychological literature, its nomological network in the context of health and well-being is not well established. Our study addresses this limitation by examining the relationship between dispositional mindfulness and a variety of health-related psychological constructs including personality, social well-being, and affective states. Data for this study were gathered from the national longitudinal studies of health and well-being called Midlife in the United States (MIDUS-II and MIDUS-III). Correlation analyses were conducted on the scores of various measures of psychological traits and a measure of dispositional mindfulness. The analysis of the nomological network of dispositional mindfulness showed positive correlations with both religiosity and overall well-being measures (e.g., Social Well-Being, Sympathy, Optimism, and Generativity), and negative correlations with maladaptive tendencies (e.g., Pessimism, Aggression, Neuroticism, and Personal Constraints). Finally, test-retest validity was positively verified by significant correlations among the variables, spanning a period of over 10 years. Articulating a nomological network of dispositional mindfulness has important implications for future research and practice as it enables the subsequent development of new measures, measurement models, and dispositional mindfulness-guided interventions for mental health.