It is well recognized that immigrants to Canada have higher unemployment rates and lower wages than Canadian-born workers. This report provides an estimate of the size of the aggregate immigrant earnings gap, accounting for immigrants’ stronger profile of observable characteristics, and discusses possible reasons for immigrants’ poorer labour market outcomes. The research to this point suggests that gaps may be due to both genuine skill differences between immigrants and Canadian-born workers, and labour market inefficiencies that prevent immigrants from making full use of their skills. In either case, there could be room to improve on immigrant outcomes through more extensive language training, faster credential recognition, or other integration initiatives. More rigorous evaluation of existing programs would also be helpful in understanding why gaps persist and how we can best address them.