Recently, the interest in ensuring integration between science and mathematics has been increasing. Taking this interest into consideration, this paper investigates whether or not a programme integrating particular attainments of science and technology, and mathematics classes in Turkey is effective. The study was performed in the educational term of 2007-2008 with 8th grade students (aged 14 and 15) of a middle school in Ankara. The workgroup in the study consisted of 90 students in total from three classrooms; two of them were the experiment group (30+30 students) and one was the control group (30 students). The mixed method was utilized in the study. The quantitative data obtained from the measurements performed with the test developed were compared using variance analysis (one-way ANOVA) and convariance analysis (ANCOVA). These findings were discussed by integrating the opinions of the teachers and the students and the qualitative findings obtained from the researcher's log. The outcomes of the study indicated that the programme, called by the researchers "Science-centred mathematics-assisted integration", increases the achievement of the students, if applied properly. Nonetheless, the outcomes also indicated that the teachers' lack of content knowledge and basic skills in science and mathematics has an adverse effect on the achievement of the students. It is believed that the outcomes of the study will make a contribution to the institutions educating sciences and mathematics teachers and to the institutions providing teacher with in-service training.