The behavior of Red Junglefowl (Gallus gallus gallus) at Chaing Mai Zoo was studied by observing and recording their general and social behavior from June 1997 to May 1998. The animals were divided into two groups : i) Caged 5 ; 2 males and 3 females ii) Free-roaming 5 – 10. Both groups showed similar behavioral patterns, but the frequency of different behaviors differed. Factors studied in this experiment were sex, age, size of body and environment factors. The free – roaming Junglefowl formed polygynous groups. During molting before breeding, their plumage became showy and beautiful in breeding season. The males crowed and exhibited frequent, courtship behavior. Males did not contribute to parental care of chicks. Females carried out incubating and brooding. There was a clear pecking order with dominant males higher ranking than females or intrasexual subordinates, but its ranks changed frequently.