The purpose of this research is to identify the teacher’s level of knowledge about the Specific Language Impairment (SLI) in teachers that work in public and parish schools in the Cercado de Lima. This was descriptive quantitative research with a cross-sectional observational design. The sample was made up of 170 teachers (prekinder, elementary and high school teachers), for that reason, a questionnaire that was created by Angles and Gutiérrez (2020) was used. This questionnaire was revised by expert judges and modified by the authors of this investigation, giving as a result a questionnaire of 29 questions divided in the following dimensions: definition, characteristics, causes, intervention and epidemiology. After analyzing the results, the teachers achieved an average level of knowledge about SLI with a 45,9%, followed by a low level of knowledge with a 30,6% and a high level of kn...