Background: The present study was conducted to assess knowledge, attitude, the practice of family planning and to study the determinants of fertility in different socio religious population in Tirupati, Andhra Pradesh, India.Methods: The present cross-sectional study was carried out among 150 study subjects using a self-administered questionnaire. The data was collected and analyzed with Epi info version 7.Results: Only 144 participants actively participated and given their consent. Majority of them have knowledge about any one method of contraception. An average of both Muslim and Hindu religion have known about the natural contraceptive methods, oral contraceptive pills and IUCD was equal and an average of 11-12% of the participant were aware about side effects of oral contraceptive pills. The objections to contraceptive preventing women from using contraceptives coming from husbands and mother-in-law were strongly agreed/agreed in Hindu and Muslim population almost similar. The religious believes were strongly agreed/agreed in Muslim women than Hindu. Even though most of the participants visited or consulted with health care professionals in health center for family planning and 3/4th of them were using contraception. While comparing the four proximate determinants of fertility, index of contraception had greater impact on fertility than others.Conclusions: The present study highlighted that most of the women have not practised and have less knowledge about modern contraceptive methods. Innovative approaches have to be planned, tested and implemented to ensure their access to information, contraceptive methods and family planning services.