The main purposes of this study were examining the effectiveness of preparatory origin teachers (POTs) in North Shewa Zone of Oromia Region and identifying factors that affect their effectiveness. Accordingly, data was collected from secondary school students; senior colleagues of the POTs, department heads, vice principals and principals as well as preparatOlY origin teachers. Questionnaires, observation checklists and unstructured interview were used /0 secure the necessary data from these sources. The data obtained through close-ended questionnaires and observation checklists were quantitatively analyzed by using frequency counts, percentages and mean scores. Data from open-ended questions and interview were analyzed by describing or narrating and interpreting to substantiate the quantitative analysis and interpretations. The result indicated that the preparatory origin teachers in the specified zone were partially or less effective as examined in terms of subject mailer knowledge, clarity, variety, task orientation, engagement, moderate-to-high success rate and other two behaviors. It was also found out that negative allitudes towards the profession, insufficiency in the pre-service trainings, recruitment criteria, the impact of plasma, lack of experiences, heavy work load, lack of cooperation, lack of sufficient instructional materials, etc were some of the factors that hinder their effectiveness. Finally, based on these findings some pragmatiC and possible suggestions were forwarded to help improve the disserved state of affairs