The aim of the study was to investigate the mathematics teaching and learning practices of secondary school teachers and to identify the gap between current mathematics teaching practices in Pakistan and best teaching practices suggested by the literature. In order to attain this aim, the researcher selected a sample of 1000 secondary school students at secondary level and 100 teachers teaching. The sample was taken in two stages. In first stage 25 public male schools and 25 public female schools were selected. Similarly 25 private male schools and 25 female private schools were also selected. Ten students from each of the sample schools were selected by using systematic random sampling technique. The study was mixed-method in nature and followed a concurrent research design in which both qualitative and quantitative data collection and analysis went parallel and the findings complement each other. The data for qualitative part were collected through semi-structured interviews of teachers and video-recorded classroom observation of students while the quantitative data were collected with the help of two survey instruments one for students and the other for teachers. The qualitative part was analyzed with the help of content analysis technique and the quantitative part with descriptive and inferential statistics. The reliability coefficient derived in a pilot study indicated that surveys were reliable enough to be used in the detailed study for data collection. The findings indicated serious gap between the current and perceived teaching and learning practices. It was discovered that teachers do talk about best practices but were not willing to apply those as they have their own many reasons for not doing so such as overworking, limited material resources and overcrowded classrooms. It was also found that the teachers did not even know what classroom practices have been recommended in educational policy documents and national curriculum of mathematics. It was pointed in survey that discussion and demonstration method are highly being used by the teachers whereas the classroom observations revealed that teachers used drill and practice method often. Further the teachers also claimed during the interview that drill and practice method is the best method for teaching and learning mathematics at secondary level. The teachers give guide books to students for memorizing various concept and subsequent drill. Although many teachers preached for conceptual understanding of mathematic yet it is lacked in classrooms. Problem solving technique of teaching is claimed to be a best and effective practice cum standard specified in National Curriculum Mathematics (2006) the data has shown that this practice is rarely used in the mathematics classrooms. It is concluded that the Pakistani mathematic secondary school teachers do not use many of the best mathematic teaching practices suggested by the literature. It was also observed in study that some of the best mathematic teaching practices are being used in private schools which are illustrated in teacher survey. But in students’ survey public school students have better perception of teaching and learning practices then private school students which is also observed in qualitative data. It has been recommended that the teachers may be oriented to use best mathematic teaching practices in their secondary school classrooms in order to develop deeper conceptual understanding among the students. Further the teachers may also be provided opportunities to develop their own knowledge and understanding of the recommended mathematics teaching practices as suggested by the national education policy and curriculum documents. It is further recommended that the future research may be conducted in order to explore how pre- and in-service training prepare secondary school mathematics teacher for the use of best mathematics teaching practices.