Extra classes are increasingly observed in both developed and developing countries. In Vietnam, a country where education reforms are at their height, extra classes are proliferating and have become a concern to society and the government. Although the government has banned extra classes that are independent of school administration, teachers often run home-based classes to supplement their income. This paper examines the extent and characteristics of extra classes among eight-year-old children, and examines the association between taking extra classes and learning outcomes (numeracy, reading, and writing skills). (Contains 7 tables, 3 figures and 2 footnotes.)