The effect of age, metacognition and learning styles on decision making has been scarcely researched among the adult population, and these studies have mostly used data collected from young adults to derive conclusions generalized towards the entire adult population. This research aimed to further differentiate the variance among the adult population by examining how much of the variance in decision making can be explained by the levels of metacognition, learning styles and by the age (young adults 18-29, middle-age adults 30-44 and mature adults 45-65) of the surveyed participants. The Metacognitive Awareness Inventory, the Learning Styles Inventory version 3.1 and the Decision-Making Questionnaire were used to examine the predictions of this study. The general results suggest that there are no significant differences between age groups in metacognition nor decision making levels. The divergent learning style had a significant relationship with metacognition. The mature adult group 3 scored higher levels of assimilative learning style while both the middle-aged group 2 and young adult group 1 had comparably higher levels of accommodating style. In conclusion, it was found that the variance in decision making may be explained by a model that includes metacognition, age and learning styles, but the results show that metacognition was largely responsible for the goodness of fit of the model. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]