Face-to-face (FTF) human-human tutoring has ranked among the most effective forms of instruction. However, because computer-mediated (CM) tutoring is becoming increasingly common, it is instructive to evaluate its effectiveness relative to face-to-face tutoring. Does the lack of spoken, face-to-face interaction affect learning gains and motivation? In this study, pairs of undergraduate students and tutors worked on physics problems either face-to-face or via a typed chat window. Although face-to-face tutoring took less time, students learned equal amounts in the two conditions. In both conditions, short tutor turns were associated with increased student learning. In both conditions, students who were more active had higher learning gains. Students in the CM condition who gained more produced more words per conversational turn. The same relationship was found in the FTF context only after back-channel feedback was taken out. A more direct measure of student activity, the relative proportion of student-initiated actions in problem-solving, was more strongly associated with student learning in the FTF context, but only for students with higher verbal SAT scores. Of the motivational variables we investigated, only students' ability goals (i.e. wanting to demonstrate one's ability to others) were influenced somewhat differently by the two contexts. These results suggest that although the difference in communication medium changes superficial characteristics of the tutoring such as its duration, most of the important pedagogical characteristics--learning gains, tutorial interaction, the activity measures associated with learning gains, and student motivation--were not affected. (Contains 5 figures, 8 tables, and 19 footnotes.)