The purpose of this study is to find out whether a web-based intervention using a mobile app is helpful for teens and young adults with sickle cell disease (SCD) in learning how to care for and manage their symptoms. 272 teens and adults with SCD will be enrolled in this study which is being conducted at the Medical University of South Carolina in Charleston SC., East Carolina University in Greenville NC., University of Miami in Miami FL., and the University of Alabama in Birmingham AL.