In this article we present the results of a qualitative research study on the pedagogical factors that influence English teaching in four public schools of Medellin, Colombia. Twelve teachers were interviewed regarding three linguistic principles: communicative competence, native language effect, and interlanguage. The data analysis led to the identification of various factors, such as teachers’ linguistic ego, view of their teaching role, and attitude towards English, which shape English teaching and are tied to teachers’ education. It was concluded that teachers’ professional development must tap into these factors so teachers can effectively revise their beliefs and adjust their practices to ensure a high quality in their teaching. En este articulo se presentan los resultados de una investigacion cualitativa acerca de los factores pedagogicos que influyen en la ensenanza del ingles en cuatro escuelas publicas de Medellin (Colombia). Doce maestros fueron entrevistados sobre tres principios linguisticos: competencia comunicativa, efecto de la lengua nativa e interlenguaje. A partir del analisis se concluyo que factores como el ego linguistico, la percepcion del papel del docente y la actitud frente al ingles son determinantes en la ensenanza de esta lengua. Se concluye que dichos factores deben ser incorporados en los programas de desarrollo profesional para que los maestros puedan revisar sus creencias y ajustar sus practicas efectivamente y asi asegurar la calidad de su ensenanza.