The study was conducted to investigate the relationship between autocratic and democratic leadership on employee performance through the mediation of organizational commitment in National Highway Authority Islamabad head office. The inquiry was conducted in a natural working environment of an organization where respondents are situated/located, that is a filed study. Simple random sampling technique was used to carry out the research using structured questionnaires which were adopted from other researcher's studies. The questionnaires were based on five-point Likert scale measuring autocratic leadership, democratic leadership, Organizational Commitment, and employee performance. 217 questionnaires were distributed among middle-level employees of National Highway Authority out of which all 217 were useable. The data was analyzed using SPSS. The descriptive statistics indicated that autocratic leadership has a negative impact on employee performance but does show the significant effect with that the other variable democratic leadership shows a significant positive impact on employee performance whereas organizational commitment does mediate the relationship between independent variables i-e Autocratic leadership, Democratic leadership and dependent variable i-e Employee Performance. Recommendations to improve employee performance under this study are provided to the organization.