Reading comprehension remains below average among Indonesian students, as reported in the National Literacy Movement Report (2022), emphasizing the need for improved independent reading skills. Supported Independent Reading Time (SIRT), a structured reading program designed to foster student autonomy, offers a potential solution. This factorial experimental study investigated the effects of SIRT and reading interest on reading comprehension. Forty tenth-grade students from SMA Dharma Bhakti Palembang were assigned to experimental and control groups, categorized further by high and low reading interest levels. Data were collected through pre-test, post-tests, and questionnaires. Results indicated significant improvement in reading comprehension (mean = 11.95) and an essential difference between groups (t = 11.89, p <.001). A partial interaction effect was found between SIRT and reading interest on inference (p =.029) and vocabulary (p =.041), suggesting SIRT’s influence varies across reading comprehension. These findings provide insights for educators to enhance independent reading strategies.