The objectives of this observational study were to use time-lapse video photography to document dairy cow behavioral patterns, examine factors affecting lying behavior, and to develop guidelines for visual assessment of free-stall usage during summer conditions in a high producing dairy. Four video cameras were placed in a free-stall pen containing 144 stalls and 129 high producing cows. The videos were recorded over a 6-d period in July 1999 and then were reviewed using 60-min scan sampling techniques. Cows were counted as lying, standing in alley without eating, standing in free stalls, or eating in each of the four sections of the pen. Temperature probes were placed on the feedline, free stalls, on both ends of the pen, and at an outside location. Relationships between proportion eligible lying and ambient temperature, feeding time, and time since milking were examined. Proportion eligible lying was equal to number of cows lying divided by total number of cows lying or standing but not eating. Cattle showed a significant pattern of temporal cyclicity in their lying behavior, with the highest average proportion of eligible cows lying at 6:00 a.m. (85%) and the lowest at 9:00 p.m. (53%). Increasing environmental temperatures and time elapsed since milking negatively impacted proportion of eligible cows observed lying when evaluated using 60-min scan sampling techniques.