Wamalwa, PeterMasibo, Edwin N.Mutsotso, Stanley N.2019-05-202019-05-202017352-885http://erepository.kibu.ac.ke/handle/123456789/1071Dismal performance in Mathematics and Science subjects poses a challenge towards realization of the Kenya National development goal of industrialization by the year 2020. The government of Kenya in liaison with the Japanese government came up with Strengthening of Mathematics and Science in Secondary Education (SMASSE) to remedy the situation. This was to be achieved through in-service training for mathematics and science teachers to improve on teacher classroom practices and student’s learning.This paper presents a study on motivation as a strategy that influence mathematics and science teachers’ participation in the inservice training. The study was guided by Rogers’s innovation-implementation diffusion theory. Descriptive survey design was used and thetarget population was 1450 teachers teaching in 275 secondary schools and 9 sub-county Quality Assurance Officers (QASO). Simple random sampling and purposive sampling techniques were used for a sample size of 438. Data was collected using questionnaires, interview schedules and an observation guide. It was analyzed using both descriptive and inferential statistics and it was found out that provision of motivation to teachers influence their participation. It was concluded that all teachers would attend INSETs if motivated. From the conclusion, it was recommended that the national SMASSE office and the MoEST should consider teachers’ views on motivationenAttribution-NonCommercial-ShareAlike 3.0 United Stateshttp://creativecommons.org/licenses/by-nc-sa/3.0/us/Article