Double-shift schooling primarily aims to extend and minimize unit costs. However, some systems only achieve these goals at the expense of educational quality. Planners may be faced with difficult choices when designing systems. Drawing on experiences on a wide range of countries, this booklet highlights the advantages and problems of double- shift systems. Comparison is made with single-shift systems, and also with systems having triple, even quadruple shifts. This booklet will be useful to planners at sub-national levels as well as national levels. It will also be valuable to head teachers and others responsible for running double-shift schools.