This paper presents a comparison of professional competence and attitude between teachers trained in Secondary Science and Mathematics Teachers (SESEMAT) Programme and those not trained in it in Eastern Uganda. The study was based on a realization that though the government provides facilitation to enable teachers undergo training through the SESEMAT programmes, teachers seem not to keenly use SESEMAT methodologies. The study was guided by two objectives: to establish whether there are differences in professional competences between SESEMAT- and non-SESEMAT- trained teachers in Uganda, and to determine whether there are differences in attitude towards teaching between SESEMAT-trained teachers and other teachers of science and mathematics. The study employed semi-experimental design. Ten secondary schools were sampled and 40 teachers were observed during lessons and also given questionnaires. Data analysis was done using the independent sample t-tests to compare the classroom professional competences and attitudes between SESEMAT-trained and non-SESEMAT-trained teachers. It was concluded that given enough time, teachers would implement SESEMAT competences / skills taught during the INSETS. The study recommended that more teachers should be encouraged to attend the SESEMAT INSETS to be able to understand the competences required during the delivery of lessons. This may help improve on the number of quality passes at Ordinary level in science subjects.