Mindset refers to a person’s beliefs about the nature of their abilities—whether they believe their ability in a given domain is malleable or fixed. We investigated whether a brief, online intervention could alter ability and non-ability traits, including mindset of intelligence, locus of control, challenge-approach motivation, grit, and performance on cognitive ability tests. Exploratory factor analysis indicated that measures of mindset, grit, and locus of control loaded onto a common self-determination factor, which was independent of a second factor reflecting fluid intelligence and crystallized intelligence. Multilevel modeling further revealed that participants who received a mindset intervention reported more growth mindset, internal locus of control, challenge-approach motivation, and self-determination. The mindset intervention did not alter cognitive ability scores or grittiness.