This paper, presented at the 2002 Physics Education Research conference, describes a study conducted to investigate small-group discussions in an inquiry-based middle school science classroom in order to determine the group and individual factors that provide support (or not) for students' sense-making discussions. Two groups were videotaped and a six-component framework was used to identify and categorize instances of sense-making: predicting; clarifying facts; describing and explaining a phenomenon or experimental result; defining, describing, clarifying, and connecting scientific concepts, procedures, processes, and representations; testing knowledge compatibility; and making requests for any of the above. Analysis revealed that there were differences in sense-making discussion across both groups and individual students. Differences across groups are explained in terms of group obligations and expectations, collaboration, and leadership. Differences across students are explained in terms of learning and social goals, science interest, work preferences, and ability.