Most economies in the world are depended on small business enterprises. They contribute significant amount to county’s GDP. Thus, small enterprises are very important instruments for economic growth. Effective measures should be put in place to boost and sustain their growth rate in the long run. Most of big companies and organizations started as small firms. The purpose of this research was to study the key determinants responsible for growth of small business enterprises. It concentrated sources of finance, quality of management and cash management. The enterprise growth theory based on the gene combination theory and pecking order theory were used. The study used descriptive survey research design. The study was located in thika town. The target population was 10,000 small and medium enterprises. A sample size of 100 small and medium enterprises was used. Respondents were selected using simple random sampling technique. Questionaire and personal interviews were used in collecting data. Pretesting of research instruments were done before the actual study. Data collected was analyzed qualitatively and quantitatively. Results were presented by use of frequency tables. The study on cost of capital, sources of finance, management skills and experience and cash management as the major factors affecting growth of SMEs. The findings revealed that easier access to source of finance was a key determinant to the growth of small and medium enterprises. The study also noted that bottlenecks in accessing source of finance lagged behind the growth of small and medium enterprises. The study noted that majority of the respondents stated that they financed their small and medium enterprises through family and friends contributions, chamas and saccos, mobile loan applications and financial institutions. It was revealed that owners with efficient management skills and experience had a positive correlation with the growth of small and medium enterprises. The study also noted that poor management skills with no experience led to collapsing of small and medium enterprises. The resulted showed that small and medium enterprises that kept records of their financial statements were growing faster than those that did not keep any financial records of their businesses. The study revealed that majority of the small and medium enterprises had been prudently managing the cash flow in the business. There is need for those intending to establiush enterprises be trained on necessary skills required to maintain, and sustain busineses for survival and growth as some had started businesses and collapsed after a short period.