||"Infrastructure Investing" has emerged to be one of most significant and fastest growing asset classes of recent years. Although a number of investors, including the Australian and Canadian pension funds, have been investing in infrastructure for many years, it is only over the past two years or so that there has been more widespread interest in infrastructure investing. This surge of interest has occurred for two distinct reasons. First, attractive market fundamentals, with strong demand for the use of infrastructure assets, and a general shortage of supply. At the same time many governments across the world face financial difficulties which are forcing them to raise infrastructure capital from the private-sector. Second, the behavior of the asset class, or the performance characteristics of infrastructure assets themselves. Such assets tend to have a high yield, steady growth in income and a low volatility. They also tend to have a very long duration, generally with a minimum of 30 years, but often 60 to 100 years, and they provide significant diversification benefits relative to bond and equity assets. Although the asset class has grown dramatically in recent years, it remains "emergent" and, as such, is subject to the risks and opportunities associated with the emergence of any new asset class. Investors starting to become familiar with the asset class need to understand precisely what it is and how it behaves. Is it, for instance, more like fixed income, private equity, real estate, or none of these? It is within this context that this paper explores a number of dimensions associated with the emergence of the asset class within Europe. Key issues include precise definitions of the types of asset that comprise infrastructure, the existing and potential size of the market, behavior characteristics and assessments of the relative attractiveness of the market across Europe.