The purpose of this study was to investigate the influence of teachers’ professional training on errors pre-school learners make as they learn English language in public pre-schools in Bungoma south sub-county in Kenya. The study adopted the social construction theory. It used descriptive survey research design with the target population comprising 3698 preschool teachers and preschool learners in top classes in Bungoma south sub-county.. Simple random sampling was used to select the preschools to participate in the study from each zone. Purposive sampling was used to select teachers and pre-school learners to participate in the study from the pre-schools in the zones. The researcher used observation schedules, documentary analysis forms and interview schedules to collect data. A reliability coefficient of 0.87 was obtained and indicated that the research instruments were reliable. The data collected from the field was examined, edited, coded and presented according to the themes of the research questions and presented in tabular form using frequencies and percentages. The findings showed that the untrained teachers contributed to 42.4% errors made in English language by pre-school learners while degree trained teachers contributed to 2.4% errors made by pre-school learners in English language. These findings indicated that professional training of ECDE teachers has a significant impact on errors made by pre-school learners in English language in Bungoma south sub-county in Kenya. This implies that teacher’s professional training influence errors made by pre-school learners in pre-schools in the research location.