According to official data (based on the income poverty line), 20% of households in Costa Rica were poor in 1994, a figure that has apparently not changed substantially since. The poverty level is currently considered to have stagnated at around 20% for more than two decades. However, the way poverty is measured has undergone methodological changes that preclude a strict comparison of the data over time. This study offers a method for dealing with the methodological difficulties and obtaining a set of comparable poverty data for the period from 1987 to 2017. It thereby demonstrates that the level of poverty in Costa Rica changed little between 1994 and 2006, but declined from the latter year onward.