This study explored the impact of individual versus two-person group testing on graduate students' achievement and motivation to learn while enrolled in a 16-lesson educational research methods course. Students in two sections of the course were exposed to the same content and instructional methods, with one exception: students in one section took three professor-created, criterion-referenced examinations (during lessons 6, 11 and 16) individually, whereas students in the other section took the same examinations with a partner with whom they could examine and discuss the test items in order to derive a common answer. At the end of the course, the motivation to learn of all students was assessed. Results revealed that students tested with a partner achieved significantly higher scores on two of the examinations and demonstrated significantly higher levels of motivation to learn than did students taking the examinations alone. Qualitative analysis of the students' written expressions concerning the course and of their comments from group and individual interviews revealed possible explanations for these outcomes. (Contains 1 table and 2 figures.)