The purpose of this exploratory study was to examine the problem-solving behaviors and perceptions of (n=27) seventh-grade students as they worked on solving a mathematical problem within a small-group setting. An assessment system was developed that allowed for this analysis. To assess problem-solving behaviors within a small group a Group Problem Solving Assessment Instrument was developed. To assess student perceptions a stimulated-recall interview was used. Data were obtained through videotapes of the students working in small groups and audiotapes of stimulated-recall interviews of the individual students. The results suggest the importance of higher level processes used when students talk about the problem with their peers. A continuous interplay of talking about the problem and doing the problem appeared to be necessary for successful problem solving and maximum student involvement. Perceptions, particularly those of higher and lower-ability students, provided an understanding of the observed problem-solving behaviors within groups. The assessment system shows promise of being a powerful tool for examining the internal dynamics of mathematical problem solving in a small-group setting. Contains 25 references. (Author)