Writing and reading are two interconnected literacy skills. In English as a foreign language (EFL) mixed-ability classes, the process genre approach (PGA) has become necessary for EFL students to exchange skills and processes of reading with writing academic paragraphs. This study examines and correlates the achievement scores of academic paragraph reading and writing among EFL mixed-ability class students. Data were collected by using the achievement tests in reading and writing among mixed-ability classes of EFL students in the preparatory year of Najran University. Data were analyzed through correlation analysis and the paired sample t-test. The results showed that the mixed-ability classes of students scored high levels in paragraph understanding and moderate levels in paragraph writing, with high values of standard deviations that reflect mixed-ability classes. The results also showed that the mixed-ability levels scored low in identifying signal words and using transition words. The results also revealed a moderate positive correlation between paragraph understanding and writing. This result indicates that PGA has a potentially positive effect in mixed-ability classes, where PGA teaching materials and assessments are effective scaffolding tools for mixed-ability reading and writing classes.