Intellectual humility is regarded as highly important by leaders in business, education, public service, and other fields. Yet, despite its apparent importance, there is little empirical research on intellectual humility. Seven studies in this dissertation investigated the nature of intellectual humility and its consequences for disagreements, and for learning in school. In Studies 1 and 2, a new self-report intellectual humility scale demonstrated good convergent and discriminant validity. Moreover, in these studies college students higher in intellectual humility were more open to the opposing view in disagreements about school material (Study 1), and adults were more open to the opposing view in disagreements about actual socio-political issues (e.g., increasing taxes to fund public education, and passing laws to limit greenhouse gas emissions) (Study 2). Studies 3 and 4 tested the associations between intellectual humility and two behavioral measures of openness. Adults who were higher in intellectual humility read more reasons justifying a socio-political position that opposed theirs (Study 3). Participants who were higher in intellectual humility also felt that they had learned more by reading others' reasons, and remained more interested in continuing to learn about the issues relative to those who were lower in intellectual humility. Participants who were higher in intellectual humility were also marginally more likely to articulate more reasons justifying a socio-political view that opposed theirs, but this association was not statistically significant (Study 4). In Study 5, beliefs about the malleability of intelligence were examined as a possible source of intellectual humility. It was predicted that a growth mindset of intelligence -- belief that intelligence is a malleable trait that can be developed -- would enhance intellectual humility because operating in a growth mindset may make it easier to acknowledge what one does not know. It was also predicted that a fixed mindset of intelligence -- belief that intelligence is a static trait - would dampen intellectual humility because having a fixed mindset may foster the perception that some people have superior intellectual abilities compared to others. To test these hypotheses, an experimental procedure was used to induce either a growth or a fixed mindset of intelligence in Study 5. As predicted, participants in the growth mindset condition had significantly higher intellectual humility and were significantly more open to the opposing view relative to those in the fixed mindset condition. Moreover, the mindset induction significantly affected participants' intellectual humility, which, in turn, shaped participants' responses to disagreement. That is, the growth mindset induction boosted participants' intellectual humility, which, in turn, made them more open to the opposing view relative to those in the fixed mindset condition. This study also found that the relations between mindset, intellectual humility and responses to disagreement were robust to participants' experiences of intellectual success and failure. Studies 6 and 7 investigated the relation between intellectual humility and outcomes that are relevant for learning in school. College and high school students higher in intellectual humility had a stronger motivation to learn, used a number of adaptive study strategies, and reported being more collaborative when working in groups relative to those lower in intellectual humility. These results suggest that intellectual humility might foster an adaptive achievement motivation that is focused on learning rather than on trying to demonstrate one's intelligence.