The investment alternatives offered by mutual funds have had a significant effect on the savings patterns of many countries. Industry research has primarily focused on the funds themselves rather than on their management companies, but like other financial institutions, these companies, also known as mutual fund families, have experienced great periods of both expansion and contraction. It is important to address the efficiency of these institutions, as well. Carlos Sanchez Gonzalez fills this gap in our knowledge with this empirical study. He develops an innovative model that considers the management stages of mutual fund companies, overcoming the traditional dispute between the different approaches used in banking and insurance research. Using data envelopment analysis (DEA) to evaluate efficiency levels, Sanchez Gonzalez investigates the Spanish case, one of the most relevant industries in the Euro market, in order to provide insights into issues that have never been explored before. His study consists of two parts. The first explains the basic concepts, offers a brief explanation of the basic DEA models, and gives a review of the most important applications to financial institutions, all while developing a unique set of industry-specific variables in order to show how to apply the original slacks-based measure (SBM) approach. The second reviews the major concepts of SBM variations and shows how they can be applied to the Spanish mutual fund family industry in order to obtain unprecedentedly accurate empirical measures of its efficiency. This ground-breaking work offers much food for thought to academic researchers and postgraduate students of management, finance, and marketing.