Behavioral phenotypes (BP) (personality, temperament) can be relatively consistent within an individual over time and across situations, and BPs can predict individual fitness and survival. Several BPs have been identified, for example, some individuals are reliably more exploratory, bold, active, or social than others. While much research has characterized these BPs in different species, their relative consistency across time and situations, and the physiology that may drive their consistency is not well understood. The objectives of this study were to determine relative consistency of BPs across different situations and time, and to determine associations of BPs with physiological processes. To measure BPs, we used 3 different behavioral tests (Novel Social Arena, Novel Object Arena, Partner Preference Task), each conducted three times with 54 Sprague-Dawley rats. To assess physiological processes, we measured glucocorticoid (GC) responses to acute restraint, innate immune responses to lipopolysaccharide, and adaptive immune responses to keyhole limpet hemocyanin. Results indicate that Social Boldness and Activity behaviors were individually consistent across tests and time, whereas Exploration behaviors were less consistent. Of the different physiological responses, GC responses were most frequently associated with BPs. Social Boldness and Exploration were associated with lower stress-induced GCs and enhanced innate immune responses, whereas Activity was associated with elevated GC reactivity, elevated basal pro-inflammatory circulating cytokines, and lower innate immune reactivity. The results indicate that certain behavioral phenotypes are more consistent across time and situations than others, and that underlying physiology may partially drive BP consistency. This line of research requires further investigation.