Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Get Your Wings (10 points): Complete the Tutorial.
Make It (20 points): Complete the Career on Easy.
Movin' Out (30 points): Complete the Career on Medium.
Rock in a Hard Place (50 points): Complete the Career on Hard.
Dream On (75 points): Complete the Career on Expert.
Aerosmith (15 points): Unlock Aerosmith as the playable band.
Jailbait (5 points): Play a song at the Nipmuc venue.
Cheesecake (10 points): Earn a 100 note streak in Career or Quick Play (Local only).
Crazy (20 points): Earn a 500 note streak in Career or Quick Play (Local Only).
No More, No More (10 points): Perform all the Encores.
Kings and Queens (20 points): Purchase all the playable characters from The Vault.
Big Ten Inch Record (20 points): Purchase all the bonus songs.
Toys in the Attic (20 points): Purchase all guitars from The Vault (Bass/Lead/Rhythm).
Same Old Song and Dance (50 points): Complete every song in the setlist and the Vault (Local only).
Score Hero (30 points): Score "325,000" or more on the song "Train Kept a Rollin'".
Get it Up (30 points): Score 2,000,000 in the Career.
Eat the Rich (30 points): Earn $50,000 in career earnings.
I Don't Want to Miss a Thing (30 points): Earn a gold star rating on a song on Medium or harder difficulty (Local only).
Gems (25 points): Hit every star power phrase on a song (Local or Xbox LIVE).
Sick as a Dog (25 points): Earn a 5 star rating for a song on Medium or harder (Local or Xbox LIVE).
Ain't That a B***h (20 points): Earn a gold star rating on a song (Local only).
Big Ones (15 points): Earn a 300 note streak in Co-op (Local or Xbox LIVE).
Cryin' (25 points): Earn a 600 note streak in Co-op (Local or Xbox LIVE).
Combination (5 points): Earn an 8x multiplier in Co-op (Local or Xbox LIVE).
Let the Music Do the Talking (40 points): Earn a gold star rating on a Co-op song (Local or Xbox LIVE).
When I Needed You (15 points): Activate Star Power 3 times in a song in a Co-op match (Local or Xbox LIVE).
What it Takes (35 points): Play 20 online ranked matches of any game type.
Deuces Are Wild (40 points): Complete all songs on the setlist as the lead guitarist (Local or Xbox LIVE, primary user).
My Fist Your Face (20 points): Win an online ranked Pro Face-Off match.
Don't Get Mad, Get Even (20 points): Win an online ranked Face-Off match.
Walkin' the Dog (20 points): Win an online ranked Pro-Face Off match by 10,000 or more points.
Soul Saver (20 points): Win a ranked online Battle Mode match with a Death Drain attack.
Love Me Two Times (40 points): Complete all songs on the setlist as the Bass/Rhythm guitarist (Local or Xbox LIVE, primary user).

Additionally, there are sixteen secret achievements, all of which are currently unknown:

Secret achievement (10 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (15 points): Unknown.
Secret achievement (20 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (15 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (10 points): Unknown.