A new item type was developed, incorporating features of "ill-structured" problems in a multiple-choice format. The problems are similar to previously developed scientific thinking tasks in requiring the examinee to go beyond the information provided; they resemble a variant of the logical reasoning item type, but demand somewhat more structuring by the examinee of the set of assumptions needed to solve the problem. A pretest was carried out to compare the new item type with two variants of the logical reasoning item type; a second study, using preexisting data, compared these two variants with one another. In neither case was there any indication that problems identified as "ill-structured" measured different aspects of ability than do "well-structured" problems. The new item type might be employed in tests of reasoning for the sake of increasing the variety of item types available for test construction, but would not be expected to extend the range of cognitive skills assessed by the tests.