This paper studies the investment performance of pension funds with a focus on their ability in implementing their intended investment strategy. We use a sample of Dutch industry-wide pension funds, which are obliged by law to report their investment performance according to the so-called z-score. The z-score is a risk-adjusted performance measure with benchmark settings predefined by Dutch law. We find that pension funds as a group cannot beat their self-selected benchmarks consistently. Applying a cross-sectional portfolio approach we find evidence that the largest pension funds outperform the smallest funds.