This research focused on adult students diagnosed with attention-deficit hyperactivity disorder (ADHD) to see if an early diagnosis made a significant difference in their academic success in college. Research into adult ADHD and especially individuals in postsecondary education has lagged behind other areas of ADHD research. The present study aims to provide a part in filling the gap by investigating the relationship between first-year grade point average (GPA) and executive functioning (EF) scores. The primary question for the research is: "is there a significant difference in college GPA and the five executive functioning EF scales between adults based on age at diagnosis?" Two groups were studied: those with ADHD diagnosed by the age of 16 and those diagnosed at the age of 17 or older. This study was performed to examine the relationship, if any, between the GPA and EF scores of voluntary participants through a survey. The target population for this study consisted of adults diagnosed with ADHD at any age who had attended at least 1 year of college. The participants were asked to complete the Barkley Deficits in Executive Functioning Scale and to disclose their GPA after completing their first year of college. How recently the participants completed their first year of college was not surveyed. Each participant was asked to self-disclose if they had been diagnosed with ADHD by a physician. Upon confirming their answer of yes, the participants were allowed to proceed to the survey stage. The survey collected the following information: Age of diagnosis with ADHD, GPA of first year of college completed and to complete Barkly Deficits in Executive Functioning Scale consisting of 89 questions. The size for each group was 36 participants for a total of 72 participants surveyed. Results did not indicate a significant difference in college GPA between the two age groups. Control of gender and age distribution to model the population should be considered in future studies. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]