This research covers how high street fashion companies manage the new product development process to meet the demands of a new market.It give some definitions in the beginning of the literature review. And the primary research presents two case studies to help the reader understand the theories in the literature review.In the conclusion, I summarize the opinions from literature review and primary research, and make some suggestions about the standard process of a high street fashion company trying to enter a new market and to a company already in this market segment and interested in expanding its brand to a new market.