During a 2 y study (February 1993–January 1995) I searched a total of 519.4 km of canal and levee banks in 304.4 h to study Florida kingsnake (Lampropeltis getula floridana) activity. I gathered and compared data on seasonal activity patterns of two populations in southern peninsular Florida, around Lake Okeechobee and southern Dade County. Snakes from both populations exhibited two activity peaks, one in spring and one in fall. The highest frequency of encounters was in March and April during the peak of the breeding season. During this time males were encountered more often than females, possibly because they are actively searching for mates. Encounter rates are constrained by temperature rather than precipitation. The majority of snakes were found in the open aboveground between 24 C to 29 C, with the highest frequency at 27 C. At lower and higher temperatures encounter rates decreased as snakes may retreat into refugia. Adults were encountered more often than juveniles. Adults are primarily diurnal, whereas juveniles exhibit crepuscular and nocturnal behaviors. An apparent ontogenetic shift in diel activity occurred at approximately 90 cm SVL, where secretive juveniles gradually become more diurnal.