This paper examined how teachers' noticing skill affects the social and socio-mathematical norms they construct in the classroom. The study was carried out with four mathematics teachers working at a secondary school in the eastern regions of Turkey. A case study among qualitative research methods was used. The data of the research were collected via videotaped lessons. The data obtained from teachers' classroom practices were evaluated performing descriptive and content analysis. Research findings show that noticing skill positively improves secondary school mathematics teachers' ability to construct social and socio-mathematical norms. In addition, it has been noticed that social norms and socio-mathematical norms are not independent of each other.