This paper examines the way in which learning quality has been conceptualised and measured in school effectiveness surveys conducted by Young Lives, a longitudinal study of child poverty. Primary school surveys were conducted in Vietnam in 2010-11 and Ethiopia in 2012-13, and surveys at upper-primary and secondary level were conducted in Ethiopia, India and Vietnam in 2016-17. The paper discusses the design of cognitive tests to assess Maths and reading at primary level, and then focuses on the development of cognitive tests to assess Maths, functional English and transferable skills at upper-primary and secondary level. In particular, the paper explores how learning quality can be conceptualised and measured in relation to "twenty-first century skills", which are increasingly seen as an important outcome of secondary education. The challenges of designing cognitive tests to measure and compare learning quality across three diverse country contexts are also explored.