In India,mutual funds have emerged to become the most important investment vehicle during the past five years due to fast growing economy,rising income levels,ease of on-line investing and wide ranging mutual fund product offerings.One of the main reasons for such growth is a large number of mutual fund product offerings and the associated investment styles,which is the central focus of this study.Managers adopt a variety of investment styles to offer wide ranging mutual fund plans which give rise to different performance levels.The task of today's fund manager has become complex and it is no more bundling a few stocks and try to outperform the market.To succeed in the highly competitive market place,fund managers need to make conscious choice regarding investment style as it may affect performance.The study attempts to develop Investment Style Index for measuring investment style of equity funds to find how investment styles affect the performance and is probably the first of its kind in Indian context as it attempts to quantify investment styles and relate it to performance of equity mutual funds.