Over the last decade, there has been an enormous growth in the availability and participation of investors in private equity co-investments. Private equity co-investments are investments made by Limited Partners (LPs), alongside General Partners (GPs) and are regarded as a means to improve investment returns and lower overall fees. As a result of the potential to generate outperformance through co-investing, the value of co-investment deal volume has more than doubled since 2012. Furthermore, more than 35% of investors plan to co-invest alongside fund managers in the near future. However, co-investing is not without its risks and challenges and requires extensive resources and expertise to build a sustainable co-investment program. Wilshire has been an active co-investor for over a decade and in this article we will examine in more detail the benefits of co-investing, its risks and the different co-investment models available to investors to seek outperformance.