The purpose of this study was to develop an assessment for screening students with reading comprehension difficulties, especially in inference-making. Based on literature review on inference-making assessment and the 2009 revised national curriculum, a 20-item assessment was created. Each item consisted of short narrative text (7 sentences) with 6th sentence is deleted, and students needed to choose one sentence among 4 multiple choice responses to complete the text in a coherent way. After a Delphi questionnaire and a pilot study, the final version of the 18-item assessment was developed. Results of a validation study showed that the new inference-making assessment was reliable and valid. In addition, ROC curve analysis indicated that the assessment had an excellent level of classification accuracy. In terms of item-level analysis, the IRT results showed that the 18 items had an adequate level of difficulty and discrimination. Finally, elementary school teachers thought that the assessment had a good feasibility in terms of its utility and efficiency. Implications and future directions were discussed.