The analysis distinguishes between firms (273 firms) on and off Science Parks in Sweden (1996-1998), in an effort to identify any element of added value which the park provides for new technology-based firms (NTBFs). The study showed some differences between the experience of firms on- and off-park in respect to innovation and marketing issues. Firms located in Science Parks were significantly more likely to have a link with a local university than off-park firms. Performance is examined under three headings: employment growth, sales growth and profitability. Initiatives to promote NTBFs on Science Parks, will yield a higher rate of job creation than policies to help NTBFs in general.