This experiment investigated the impact of different types of critical thinking instruction and dispositions on bias in economics students' (N = 141) reasoning performance. The following conditions were compared: (A) implicit instruction; (B) implicit instruction with practice; (C) implicit instruction with explicit instruction and practice; (D) implicit instruction with explicit instruction, practice, and self‐explanation prompts; and (E) implicit instruction with explicit instruction, practice, and activation prompts. Results showed that explicit instruction combined with practice is required to improve critical thinking (i.e., conditions A/B < C/D/E). Prompting during practice had no added performance benefits. Participants' dispositions toward actively open‐minded thinking predicted their pre‐test and post‐test scores but did not interact with instruction condition, suggesting that receiving explicit instruction combined with practice was equally effective for all students. Copyright © 2014 John Wiley & Sons, Ltd.