This study examines the relationship between investment performance and concentration in active equity portfolios. Active management is dependent on the success of two important components in the investment process – stock selection skill and portfolio management. Our study documents a positive relationship between fund performance and portfolio concentration. The relationship is stronger for stocks in which active managers hold overweight positions, as well as for stocks outside the largest 50 stocks listed on the Australian Stock Exchange (ASX). We find that more concentrated funds tend to be those implementing growth styles, having smaller aggregate assets under management, being institutions that are not affiliated with a bank or life-office entity, whose funds experience past period outflows, and who are benchmarked to narrower indexes than the S&P/ASX 300.