ABSTRACT The Second National Education Regulatory Framework (2nd LDB), enacted in 1971, changed the grade configuration of schooling levels in Brazil. This change made it challenging to construct a valid and reliable education spending data profile for 20th century Brazil. Previous work on the economic history of education in Brazil used the data provided according to the thesis of Maduro (2007). Wjuniski (2013) used that database and ran structural break tests and concluded that the Brazilian government underinvested in the expansion of secondary education. However, Wjuniski did not consider problems concerning: (i) data reliability and (ii) the effects of the 2nd LDB on education expenditure data. This paper shows that data on education spending in Brazil does not allow us to assert that there was an underinvestment in secondary education from 1971 onwards.