The quality of English language education in universities is vital in preparing individuals for the increasingly globalized world. Assessing the efficacy of English teaching programs is therefore crucial to ensuring such quality. Consequently, this study aims to evaluate the optional English preparatory program of a state university using the CIPP model dimensions: context, input, process, and product. The current study employs a mixed-methods research approach, combining quantitative and qualitative data to address the research questions. The study sample comprised 247 preparatory graduate and 77 preparatory students, as well as 6 lecturers. In the quantitative part, The CIPP scale (Context, Input, Process, and Product), developed by the researchers based on item analysis, second-order exploratory factor analysis, reliability analysis, criterion validity, and content validity, was used to determine the strengths and weaknesses of the English preparatory program based on responses of participants to the items in four dimensions of the scale. The qualitative aspect of the study involved obtaining responses from participant students through open-ended questions and conducting semi-structured interviews with lecturers. These responses were analyzed, and the resulting excerpts were used to support and complement the findings obtained from the quantitative findings. The results indicate that the participants were highly satisfied with the optional nature of the program and held positive perceptions of it. However, some improvements, particularly in the physical conditions of the program's context dimension, such as the library, laboratory, and school building, were required. The findings from the input and process dimensions reveal the importance of increasing target language use and prioritization of speaking skills in the product dimension. The developed CIPP scale, which is statistically reliable and valid, can be utilized by researchers to evaluate English preparatory programs using the CIPP model. The study concludes by offering several key recommendations for creating a more effective English preparatory program based on the findings.