The article examines how Sharpe's single-index model can help build better investment portfolios in the Indian mid-cap sector. By analyzing data from the Nifty mid-cap 100 index, the study found that portfolios created using Sharpe's model had higher returns and lower risk compared to the market benchmark. The optimal portfolio consisted of 11 securities from eight different sectors, showing good diversification. While the model may not perform well in extreme market conditions, it is a useful tool for individual investors and portfolio managers worldwide. This study demonstrates the effectiveness of Sharpe's model for mid-cap companies in India.