The ability to think critically and creatively is essential for students to help them thrive in the 21st century. Creative and critical thinking can be measured through problem solving because the assessment contains tasks that require students to find problems, analyze and evaluate problems, and work out the solutions. Therefore, this study was designed to develop a critical and creative reading assessment model based on problem solving and test the validity and reliability of the assessment. The assessment contained problem-solving essay tests that were presented in the form of stories. The material stimulus was news item texts that focused on social problems. The data collected were in the form of mean scores of expert validity testing and practitioner inter-rater reliability testing. The assessment was tried out to 36 students. The validity of the instrument was analyzed descriptively, while the reliability of the instrument was analyzed using analysis of variance (ANOVA) and intraclass correlation coefficients (ICCs) with SPSS 26. The results of the study indicated that the mean score of the expert validity test was categorized high (3.74), and the result of the reliability test showed that there was no difference in the inter-rater assessment because p > 0.05 and the ICC obtained was excellent (r[subscript xx] = 0.716). It can be concluded that the assessment developed in this study was valid and reliable, and thus can be used as an assessment to improve the critical-creative reading skills which are the essential skills needed to survive and thrive in the 21st century.