Abstract: This review of the research literature on difficulties with problem solving in mathematics shows us that problem solving in mathematics is a complex process which requires an individual who is engaged in a mathematics task to coordinate and manage domain-specific and domain-general pieces of knowledge. It also suggests that (i) the mathematics content level of the problem which students at different year levels of schooling will be able to solve successfully and (ii) the different strategies or heuristics which students at different year levels use to solve the same mathematical problems must govern the design of problem-solving curricula at the various year levels of schooling.