This paper, based on the agglomeration economic theory, attempts to examine what types of R&D collaborations can contribute to firm performance in a cluster. Results from the industrial data together with a questionnaire survey of 165 Taiwan's ICT firms indicate that firms inside the cluster (a science park) outperformed firms outside the cluster in terms of seven-year averaged gross profit rates. Moreover, R&D collaborations with research institutions enhances a firm's profits as firms locate inside the cluster whereas R&D collaborations with universities and receiving licensed technologies from the government improves a firm's profits as firms locate outside the science park. This paper also provides implications for both practitioners and policy makers regarding science parks.