Scarce human and fiscal resources of high value are spent in the field of education. Thus, the concept of efficiency, and particularly technical efficiency, that refers to the maximization of outputs at a given set of inputs, can be a possible contribution to the design of education policy and administration; mostly at a time of economic crisis as this in Greece, research could assist in formulating proposals on how resources are actually used within education structures/services, as well as in providing guidance to those responsible for the internal allocation of funds so as to secure greater educational results and benefits. The aim of this study is to measure the degree of technical efficiency of the 23 High Schools (Lyceums) in the Prefecture of Fthiotida in Greece, using the model of Data Envelopment Analysis and explore the factors that could interrelate with these measurements. The results provide evidence that a low percentage of school units (34.8%) achieves maximum technical efficiency. Proposals for improving the technical efficiency of the specific schools are also made.