Abstract
Bullying phenomenon in primary schools has emerged as a worldwide problem and thus constitutes a significant threat to the mental, social, emotional and physical wellbeing of pupils in school environment. It is a common destructive form of behaviour among the pupils that has been given serious concern to educational researchers and stakeholders. Despite several efforts to curb the menace of bullying among pupils in schools, it growing awareness become devastating and inhibits learning. Consequently, this study therefore investigated “sustainability effect of cognitive self-instruction on bullying behaviour of pupils in primary schools, Kwara state, Nigeria. This study adopted a non-randomized pretest, post-test experimental and control group design. The population for this study comprised of all basic-schools’ pupils in the study area and the target population comprised of pupils in primary Five. The researchers used NICHQ-Vanderbilt Assessment Scale-Teacher Informant (NICHQ-VAS-TI), Bullying Identification Questionnaire (BIQC), Pupil’s Peer Relation Instrument (PPRI) and Cognitive Self-instructional Training (CSIT). Multivariate Analysis of Variance (MANOVA) was used to test the only hypothesis at 0.05 level of significance. The finding of this study revealed that, there was significant sustainability effect of cognitive self-instruction on bullying behaviour of basic schools’ pupils in Kwara State after cessation of treatment variable for four weeks, this is evident in the P value .000 which is less than 0.05 alpha level (.000 < 0.05). It is therefore recommended among other things that CSI should be brought to the forefront among other therapies and used to reduce bullying and sustain desired behaviour among basic schools pupils. Also, educational psychologists, teachers and counselors should be made available in basic schools to modify the cognitive thoughts of pupils towards bullying behaviour through Cognitive self-instructional training to avert the re-occurrence of bullying.

Keywords
Bullying, Cognitive self-instruction, Sustainability Effect, Pupils, Deficient empathy