This study explored the effects of reading strategy training delivered online through an experimental scaffolding tool in comparison to similar training delivered by a teacher, and a control condition. The instructional design of the tool followed scaffolding design guidelines, reciprocal teaching model, and principles of multimedia design. The training provided metacognitive reading strategy instruction to improve reading comprehension through multiple strategies using multiple texts. The participants were 87 college students studying English as a Foreign Language (EFL) at an English medium university in Turkey. At pretest, the control group had scored significantly higher in reading comprehension based on a standardized measure. Both of the experimental groups significantly improved their reading comprehension and metacognitive strategy awareness, while the control group's reading and engagement scores decreased. The in-class experimental group also improved on the engagement scale. No significant difference was found between the experimental groups or compared to the control group in reading comprehension. The findings have implications regarding institutional policies for teaching reading in EFL and online reading strategy design at the tertiary level.