High School Sweethearts Zac & Vanessa
updated 11/10/2008 AT 01:00 AM EST
•originally published 11/10/2008 AT 01:00 AM EST
Efron, 21, and Hudgens, 19, began dating in early HSM days in 2005, and their relationship strengthens by the year. Says HSM director Kenny Ortega: "The chemistry they have has grown big-time."