A goal of this study was to examine elementary preservice teachers' (PSTs) ability to contextualize and decontextualize fraction subtraction by asking them to write word problems to represent fraction subtraction expressions and to choose prewritten word problems to support given fraction subtraction expressions. Three themes emerged from the data: (a) subtraction problems were represented by an incorrect redefinition of the whole; (b) the type of unit chosen for the whole (e.g. cups, gallons, pounds vs. pizzas, pies) influenced the success of PSTs in representing Separate (Result Unknown) context problems for subtraction; and (c) the structure of the problem influenced PSTs' performance in writing subtraction word problems.