This study explores problem solving practices in a gifted and talented mathematics classroom in response to the calls for investigating problem solving as a sociocultural cultural activity rather than a cognitive activity of individuals. Therefore, we used a socio-mathematical norm perspective for our investigation. Data consists of forty-three mathematics lessons in a gifted and talented classroom. We used the two dimensions of a socio-mathematical norm (student and teacher) to analyze the observational data. The findings revealed a social norm regarding different solutions that reflect the classroom's micro-culture in terms of problem solving and students offered mathematically different (especially easy, simple, or effective ones) and sophisticated solutions which pointed out a socio-mathematical norm about mathematically different solutions. We observed an explicit talk on different solutions. However, the classroom community lacked a socio-mathematical norm regarding evaluations of mathematically different solutions based on criteria such as easy, simple, effective, or sophisticated. A lack of such a norm resulted in low-level problem-solving practice which was not expected from gifted and talented students. We offer practical implications for the dynamics of a classroom where gifted and talented students engage in problem solving activities and theoretical implications regarding the two dimensions of a norm.