This qualitative study explored the interactions of six triads of Year One students in the United Kingdom (n = 18; mean age = 5 years, 7 months; 9 female) investigating interpersonal regulation of learning, social dynamics, and group dialogue, evident in instances of productive collaboration during problem-solving activities. Group activity was captured through video (total footage = 8 hours) and subjected to two sequential phases of qualitative analysis, undertaken by three researchers: (1) comprehensive qualitative descriptions of group activity, and (2) multidimensional analysis of group interaction with a focus on interpersonal regulation of learning, social dynamics, and group dialogue. Consistent with prior research, the findings show that productive collaboration, though prevalent only in some groups, was characterized by (a) distributed forms of co-regulation where all members took turns in taking regulatory roles; (b) positive social dynamics marked by equitable patterns of participation, playful interludes, uptake of contributions, and use of persuasive language in the event of disagreements; and (c) use of exploratory forms of talk (e.g., asking questions and volunteering reasons) directed toward the achievement of task goals. Different positional preferences were identified among the most regulated students, who consistently assumed leading roles in their groups.