The purpose of this study was to determine whether providing students with continuous written instructional support or fading written instructional support (scaffolds) better prepares students to construct scientific explanations when they are no longer provided with support. This article investigated the influence of scaffolding on 331 seventh-grade students' writing of scientific explanations during an 8-week, project-based chemistry unit in which the construction of scientific explanations is a key learning goal. The unit makes an instructional model for explanation explicit to students through a focal lesson and reinforces that model through subsequent written support for each investigation. Students received 1 of 2 treatments in terms of the type of written support: continuous, involving detailed support for every investigation, or faded, involving less support over time. The analyses showed significant learning gains for students for all components of scientific explanation (i.e., claim, evidence, and reasoning). However, on posttest items lacking scaffolds, the faded group gave stronger explanations in terms of their reasoning compared to the continuous group. Fading written scaffolds better equipped students to write explanations when they were not provided with support.