The purpose of this study was to examine the influence of Heads of schools who adopt democratic leadership style on teachers‘ work performance in public secondary schools in Ilemela Municipal Council in Mwanza-Tanzania. The study was guided by three objectives namely; to investigate how democratic leaders involve teachers in decision making; to find out how heads of schools who adopt democratic leadership style delegate duties to their teaching staff and to ascertain how Heads of secondary schools communicate with their subordinates. The study employed a Mixed Research Approach and a Convergent Parallel Mixed design for data collection and analysis. Data was collected through questionnaires and interviews. The study sampled 6 schools from a total of 27 secondary schools in Ilemela Municipality from which 91 teachers and 6 headmasters participated in the study. The study found that teachers were likely to increase their performance in schools whose heads practiced democratic leadership style by involving their subordinates in decision making, delegating duties and using amicable means of communication. The study recommended that more efforts are needed to impart in heads of schools leadership skills, develop their professional career through on job and off job trainings and ensure continuous monitoring of their day to day activities for the purpose of increasing performance in all public secondary schools in Ilemela Municipality.