One of the most important reasons to investigate human metacognition is its role in directing how people study. However, limited evidence exists that metacognitively guided study benefits learning. Three experiments are presented that provide evidence for this link. In Experiment 1, participants' learning was enhanced when they were allowed to control what they studied. Experiments 2a-d replicated this finding and showed contributions of self-regulated study to learning. Experiments 3a and 3b showed that, when forced to choose among items they did not know, participants chose the easiest items and benefited from doing so, providing evidence for the link between metacognitive monitoring/control and learning, and supporting the region of proximal learning model of study-time allocation.Keywords: metacognition, study-time allocation, region of proximal learning, education, memoryOne of the best reasons to study metacognition is because it has the potential to play a large part in guiding how people study and, as a result, in how effectively they learn (e.g., Benjamin, Bjork, & Schwartz, 1998;Dunlosky & Hertzog, 1997;Metcalfe, 2002;Metcalfe & Kornell, 2003, 2005T. O. Nelson & Narens, 1990, 1994. People use memory monitoring, especially judgments of learning (JOLs), to decide which items to study and how long to spend on them (e.g., Mazzoni, Cornoldi, & Marchitelli, 1990;Metcalfe, 2002;T. O. Nelson, Dunlosky, Graf, & Narens, 1994;T. O. Nelson & Leonesio, 1988;T. O. Nelson & Narens, 1990;Son & Metcalfe, 2000). The central question addressed here is, does such metacognitively guided study lead to effective learning? The answer can be arrived at by asking more basic questions. What should people choose to study? What do people choose to study? And, are they the same? The answers to these questions have implications for pedagogy, how learning works, and the debate over the accuracy (or lack thereof) of metacognitive monitoring and control as well as theoretical implications for current models of study-time allocation.