Students' intrinsic motivation to read, which is relevant to all forms of learning, tends to decline throughout secondary school. Based on self-determination theory (SDT), this study examines whether this downward trend is slowed when students perceive greater autonomy support in the classroom. We used large-scale panel data from the NEPS comprising N = 8193 students in Germany who reported their intrinsic motivation to read and their perceived autonomy support from German teachers at annual intervals from fifth to eighth grade. Scalar longitudinal measurement invariance was found for intrinsic reading motivation (IRM) and teacher autonomy support (TAS). A dual change score model showed a decline in IRM and a negative, non-significant decrease in TAS over time. Confirming our hypothesis, the decline in IRM was slowed by earlier levels of TAS. We discuss methods to counteract the decline in intrinsic reading motivation.