The study attempts to find out administrative effectiveness of senior secondary school principals in relation to leadership styles and gender. The study was descriptive type in nature. Sample for the study was 216 senior secondary school principals. Administrative Effectiveness Scale in order to measure administrative effectiveness of principal’s tool constructed by the researcher and Leadership Preference Scale standardized by L.I. Bhushan (2005) was used to assess Leadership styles of Government Senior Secondary School Principals. This Likert type 30 items scale measures authoritarian vs. democratic leadership styles of School Principals. Further, data were analyzed through two way ANOVA and t-test. Findings of the study revealed that Leadership styles and Gender on Planning, Decision-Making, Communication dimensions and Overall Administrative effectiveness of senior secondary school principals. Whereas in case of Organizing and Motivating and Reinforcing dimension of Administrative effectiveness no interactional effect of gender and leadership styles was found to be non-significant.