In previous reviews of studies comparing explicit and implicit instruction (Krashen, 1981, 1982, 1999, 2003), the author argued that explicit instruction will show a positive effect only when the following conditions for the use of the conscious Monitor are met: (1) the acquirer consciously knows the rule or the meaning of the item--that is, has studied it; (2) the acquirer is thinking about correctness or focused on form; (3) the acquirer has time to apply the consciously learned knowledge. He also concluded that, even when these conditions are met, the impact of explicit instruction is, at best, modest and that the implicit condition consists of what can only be described as impoverished comprehensible input. These conclusions hold for a comparison of explicit and implicit instruction done by Magnusson and Graham (2012). Subjects in their study were adult (mean age 25) students of English as a foreign language, taking classes in an English program at an American university. The researchers did not collect data on their subjects' previous exposure to English, but it is safe to assume that subjects had studied English in their own countries and were well-educated, which means that they were experienced language students and were used to explicit instruction. Magnusson and Graham's results are of interest. They are consistent with the view that explicit instruction is limited, producing an effect only when severe conditions are met, and that this effect is modest. They are also consistent with the hypothesis that language acquisition requires that input be interesting and contain items that the acquirer is ready to acquire. (Contains 1 table.)