There are two puzzles in the software competition literature: whether both proprietary and open source software will survive and how producers of proprietary software differentiate themselves from open source competition. I address both puzzles by analyzing competition between a firm producing proprietary software and a community producing open source software. If the firm faces no competition, then the software caters to less technologically savvy individuals. When facing competition, the open source software caters to the most technologically savvy individuals, leading the firm to target even less savvy individuals than it would when acting as a monopolist in order to differentiate its software from the open source option. The open source movement, then, may not be an unalloyed success as the growth in open source can be tied to deterioration in the proprietary software. Given that both types of software survive by catering to different segments of the market, an important avenue for research will be to analyze the stability of the underlying segments and the corresponding welfare implications. > >