Experts and intermediates fundamentally differ in the ways they explain subject matter to novices. Experts provide less details but in a highly coherent format, whereas intermediates provide many additional details but in a format with low coherency. In a recent study, we found that experts’ explanations enabled novices to acquire more transferable and flexible knowledge as opposed to explanations by intermediates mainly due to the higher coherence of experts’ explanations. In order to investigate more directly how experts’ and intermediates’ explanations differently triggered novices’ processing of the explanations, we conducted a think-aloud study. Results indicated that novices learning with an expert’s explanation processed the explanations deeper than novices with intermediates’ explanations. In line with this, deep processing was significantly related to novices’ transfer. Thus, expertise can be regarded as an essential prerequisite for generating effective instructional explanations that engage novices to process the subject matter deeply and to generate transferable knowledge.