The purpose of the study was to examine the prevailing children’s problem behaviour and their effects on class activities in pre-schools in Effutu Municipality of Ghana. The study adopted the concurrent mixed methods design. Data were collected through a semi-structured interview schedule and questionnaire. The stratified random sampling technique was used to aid the selection of 15 schools from the Municipality. Simple random sampling was used to select 45 respondents from schools to respond to the questionnaire and purposive sampling was used to sample 15 participants for the qualitative data. The quantitative data was analysed using frequencies and percentages while the qualitative data were analysed thematically. It emerged from the study that the predominant types of children’s problem behaviour which teachers encountered were; aggression, non-compliance, destructiveness, refusal to take instruction and intentional destruction of property. Among the effects of the problem behaviours the study revealed were inattention from class activity thereby impeding participation in academic activities; breeding of social exclusion from peers, the behaviour challenges resulting in violent actions (behaviour) and other misbehaviour against others. Based on the findings, it is recommended that Effutu Municipal Assembly, Winneba Educational Directorate and the headteachers from the selected schools for the study should organize programmes in collaboration with the early childhood unit on how to cope, prevent and deal with problem behaviour and its effects to ease the burden of parents and teachers and also help the learners to benefit from their academic activities. Early childhood education teachers should also make changes to their lesson delivery strategies by asking learners to read out loud, and by actively engaging the supposed disruptive learners more often to improve their concentration and class participation.