The study examined the level of parental involvement in school adjustment in lower primary schools in Osun State. It also investigated the effect of parental socio-economic status on parental involvement in pupils' school adjustment. It further investigated the relationships among home variables, school variables and parental involvement in school adjustment. The study employed correlational research design. The population consisted of parents of lower primary school pupils in Osun State. The sample size consisted of 300 parents. An instrument titled 'Parental Involvement, Parental Support and Family Education on Pupils' Adjustment Questionnaire'; (PIPSFEPAQ) was developed and validated before used. Three research questions emanated from the study. Data collected were analysed using simple percentage and multiple regression analysis. The results among others revealed that 36.6% of the respondent indicated that there was high level of parental involvement in school adjustment. It further showed home variable (r = 0.824, p < 0.05) and school variable (r = 0.815, p < 0.05) are significantly correlated to parental involvement. The study concluded that parents have a lot to do in creating a conducive home environment that would promote pupils' adjustment in schools.