The study assessed the home environment of preschoolers. It determined the level of involvement of parents. It further determined the interaction effect of home environment and parental involvement on preschoolers’ readiness for primary school education. These were with a view to providing information on the factors that could influence readiness in preschoolers. The study adopted the descriptive research design. Parents of preschoolers in Osun State constituted the population for the study. The sample consisted of 300 parents from twelve schools. The samples were selected using multistage sampling procedure. Six Local Government Areas were selected from the three Senatorial Districts in Osun State using simple random sampling technique. From each Local Government, two private schools were selected using simple random sampling technique. From each of the 12 nursery schools, 25 parents were selected using purposive sampling technique. An instrument titled: Questionnaire on Home Environment, Parental Involvement and Preschoolers’ Readiness (QHEPIPR) was used to elicit information from the respondents. Percentages, frequency counts, t-test and ANOVA were employed to analyse the data. The results of the study showed that high percentage (71%) of preschoolers have homes that stimulate them for education by provision of educational materials, conducive reading atmosphere, good habits, monitored hours of television viewing, learning something new daily, deliberate conversations daily, planned time-out with the children, and punishment for misbehaviours. 14.0%, 70%, and 16% of the respondents have low, moderate and high level of parental involvement in preschoolers’ education. Also, the results showed that the home environment and parental involvement would significantly determine preschoolers’ readiness for primary school education (N=300, t=-59.996, p < 0.05) and (N=300,t = 21.483, p < 0.05) respectively while the interaction effect of home environment and parental involvement would also significantly determine preschoolers’ readiness for primary school education (N=300,F = 689.479, p = 0.000).The study concluded that home environment and parental involvement significantly determined preschoolers’ readiness for primary school education.