The study sought to determine the extent of usage of Igbo Language as a medium of instruction and interaction in the lower basic classes in Enugu North Education Zone, Enugu State, Nigeria. Four research questions guided the study. The design was a descriptive survey. The population consisted of 2069 teachers (198 Head teachers and 1,871 Classroom teachers) in Enugu North Education zone of Enugu state, public and private schools inclusive. The sample was 200 teachers (50 Head teachers and 150 Class teachers) drawn from the population using stratified random sampling technique. The instrument used for data collection was researchers developed questionnaire titled "Mother-Tongue Based Schooling Questionnaire" (MTBSQ) which was face validated by experts in Igbo Language and Measurement and Evaluation from Federal College of Education, Kotangora, Niger State. The reliability estimate of MTBSQ established using Pearson's co-efficient formula was 0.86. Findings indicated very low extent of the use of mother tongue (Igbo Language) as a medium of instruction and interaction; schools and parents preferred the use of English Language (L2) as a medium of instruction and interaction; and indigenous materials and textbooks in mother tongue were not available or used for instruction. By educational implication, this is a negation of the National policy stipulation on the usage of mother-tongue for instruction in Nigerian schools. The researchers therefore recommended that Government should lay emphasis on total implementation of the National Policy on Education with particular reference to usage of mother-tongue as a medium of instruction in pre-primary and primary schools in Nigeria. Also, parents and care-givers should be educated on the need for them to interact with children in their mother-tongue.