Older schoolchildren typically perform better on academic achievement tests than younger students in the same classes. Studies looking at an array of countries, grade spans, and subjects have found that age differences of even a few months do matter. Relative-age effects introduce an arbitrary bias that favors older students. These effects are a well-established fact as old as standardized testing itself--and they have been addressed head-on in the past. To see the path forward toward greater fairness in testing through age allowances, this article looks back at its history: describing age allowances in action, the impacts on equality, and hazards ahead. The author concludes with making the case for extending age allowances.