A savings and credit cooperative society (SACCO) is an association of persons who have come together with an aim of pooling their resources together for economic benefit. Kenyan SACCOs play a key role in wealth creation, poverty alleviation, and employment. Kenyan SACCOs have high growth potential but are bedeviled by challenges like strong competition from commercial banks, insufficient capital, slow rate of information technology adoption, inefficient loan pricing strategies and weak governance. The SACCO sector is growing at the rate of 20% per annum but has potential for further growth. This raises a question as to which strategies SACCOs are adopting to enhance growth. Previous researches did little to investigate effect of competitive strategies on growth of SACCOs despite the challenges dogging the sector hence this is a gap that needs to be filled. It is against this backdrop that this study sought to investigate the effect of competitive strategies on growth of SACCOs in Tharaka Nithi County, Kenya. The general objective of the study was to investigate the effect of competitive strategies on growth of SACCOs in Tharaka Nithi County, Kenya. The specific objectives were to determine the effect of market development, product development and cost leadership strategies on growth of SACCOs in Tharaka Nithi County, Kenya. The study adopted descriptive survey research design. The study location was Tharaka Nithi County, Kenya. The population of the study was the 10 SACCOs in Tharaka Nithi County. The sample size was census of the 52 managerial staff of the 10 SACCOs. Data was collected using structured questionnaires. Validity was ensured through use of experts who were the supervisors. Reliability was determined by the test-re-test method. Data analysis was facilitated by use of the statistical package for social sciences (SPSS) version 21. The results obtained from the study indicated that market development, product development and cost leadership strategies significantly influenced membership, loans issued and return on equity of the SACCOs at 5% significance level. These findings implied that the competitive strategies significantly influenced growth of SACCOs in Tharaka Nithi County, Kenya.