This study was to find out the leader effectiveness among the secondary school principals in Kerala in terms of their gender, age, experience and type of management of their school. The investigator approached 260 secondary schools Principals throughout the Kerala to collect information regarding their leader effectiveness. The study found that 39 percentages of the total sample exhibit effective leader behaviour. Nineteen percentages of principals shows problem leader behavior while 42 percentage reveals inefficient leader behavior. It also found that among the effective leaders, the percentages of females, age group 2 and experience group 2 are significantly higher than their males, age group 1 and experience group 1 counterpart. The study also found that there is no significant difference exists in leader effectiveness based on the type of management of their school. The study suggests the need for effective leadership training programme for heads of secondary school in Kerala.