The Disney star turned 19 on 20 August (11), and began the festivities two days early as she was at Kim Kardashian's wedding on the day of her actual birthday.
Lovato held a glam rock-themed bash at the Madhouse in Hollywood on 18 August (11), where she was joined by Derek Hough, and she continued to celebrate on Tuesday night (30Aug11) when fellow Disney star Tisdale took her out for a special dinner.
In a post on her Twitter.com page, Lovato writes, "Had such a fun dinner tonight with ashleytisdale... Such a genuine, sweet, funny girl. Love you ash. Thanks for my late bday din (birthday dinner)!"
Tisdale replied, "Aww love u 2 babe! Im so proud of u and can't wait for (new single) UNBROKEN to drop. Let's do dinner again soon!"