The effect of text difficulty on metamemory for narrative and expository text was investigated. In Experiment 1, we found an interaction between type of text and type of question (thematic or detailed). For readers of narrative texts, correlations between predicted and actual performance were highest for detailed questions, but this pattern was reversed for readers of expository texts. Next, text difficulty was explored as a possible factor affecting metamemory accuracy. In Experiments 2 and 3, metamemory accuracy was a nonmonotonic function of text difficulty. Subjects made remarkably accurate predictions of future performance (mean G > .6) for both narrative and expository texts that were of intermediate difficulty (approximately a 12th-grade reading level). We propose an optimum effort hypothesis, predicting greatest metamemory accuracy when the texts are of intermediate difficulty.