|Hair Color:||Light Brown|
|Family:|| Carrie Costigan (mother)|
Vic Volberg (father)
|Interests:||Medicine, chess, skiing|
|Awards:|| 5th at Med Camp|
|First appearance:||"The Second Time Around"|
|Last appearance:||"First and Last"|
Grant is the cousin of Ashley Juergens's best friend, Griffin. Like all the other men in his family, he has a name that starts with a "G." He first appears in "The Second Time Around" when Griffin decides to set up Ashley on a date, by sending Grant to deliver her a pizza. Grant admits that he's older than her and has had sex before, but doesn't want to pressure her to do the same. This moves her to decide that she wants to make her own decisions about sex, including getting on the birth control pill.
In Season 3, he decides he wants to switch to Grant High to continue pursuing a relationship with Ashley, against Ashley's wishes. After not getting her way with Ricky, however, Ashley tells Grant she'll give him a shot even though she really doesn't want to date him, in an attempt to make Ricky jealous.
He dated Grace, and revealed his love for her in Mirrors.
Grace leaves for Zimbabwe to work with Jeff, her stepdad, as a volunteer who takes care of newborns. In When Opportunity Knocks, Grace returns from Zimbabwe, and Grant finds out that Grace cheated on him with a new guy, named Daniel. He is at dinner with Griffin and Peter, (who are now official) and Griffin plants the idea into his head. What Grant doesn't know, at first, is that they've kissed several times and they've slept together. He tells Grace that he hopes that they can still be friends, to which Grace is shocked, and she tells him that that's a little too nice, even for him. Then she asks him what he did, implying that Grant may not be so truthful after all.