Personal decision-making is a core element of self-determination and quality of life for individuals with intellectual and developmental disabilities (IDD), however, they have traditionally been appointed a guardian to make decisions for them. Guardians are encouraged to involve their wards in decisions, but this comes with challenges as many are unsure of how to include their wards in decisions and must carefully balance managing risks with promoting self-determination. Despite the important role that individual decision-making plays in self-determination and quality of life, there have been surprisingly few research studies that focused on understanding how guardians involve their wards in decision-making, or factors that can influence the opportunities guardians' give their wards to participate in decisions. The aim of this study is to describe guardians' perceptions of wards' competence to make decisions at different levels of risk and its association with guardians' willingness to involve their wards in decisions. A secondary aim was to explore the relationship between perceived competence and involvement in decisions with broad educational, vocational, and independent living outcomes. Eighty-one guardians of adults with IDD in the US completed an online survey. The survey was developed based on three core constructs: involvement of ward in decisions, competence of ward to make decisions, and risks associated with decisions. The questionnaire included 15 different decision-making scenarios at three different levels of risk. Participants answered two Likert-type questions about each scenario; one for rating the involvement of their ward in decisions and one for rating the competence of the ward in making decisions. Findings showed that guardians' perception of their wards' competence in decision-making was highly correlated with how involved their wards were in the same decisions. Both how competent wards were perceived to be by their guardians and how involved wards were in those decisions decreased as decisions became more risky. Higher perceived competence and higher involvement were also associated with higher educational achievement and employment status, but were not associated with the current living status of wards. Implications and future directions are discussed. [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.]