The bill was passed by the Senate on Wednesday afternoon, the final day of the 2010 legislative session, in a 27-8 vote. The House had passed the same version earlier in the day in a 36-29 vote.
Debate on the bill went late into the night on Tuesday.
Bill co-sponsor Sen. Michael Johnston (D-Denver) said Wednesday in his final plea in front of the House, "Let the educators of the state show you, that wherever a child comes from, when they walk into the kindergarten classroom in the State of Colorado, we will promise them that 13 years later they will be ready for college, and ready for career."
Former teachers serving in the House have been vocal opponents of the bill, which backers say will help Colorado's chances of winning federal education reform funding.
Democratic Rep. Nancy Todd says the bill has sent a message to teachers that education is "all up to them."
Although the Colorado Education Association says there is still much to be done, CEA President Beverly Ingle says thanks to several amendments, the bill is much improved.
"There are certain things that we needed to make sure were in there for our teachers," Ingle said.
Ingle told 9NEWS members of the CEA worked countless hours to put in what they perceive as necessary checks and balances. Among them was creating an avenue for recourse when educators receive poor reviews.
"We now have a challenge procedure in there that goes outside of the school district, that is important to our members for their due process," Ingle said.
The CEA also says they worked hard to ensure much of the implementation of the new law will be overseen by a governor's council made up of several of the stakeholders, including teachers, students, administrators, and members of the CEA.
Under the bill, teachers will be evaluated every year and half of their rating will be based on whether their students improved during the school year.
Teachers would only earn tenure status after they have increased student performance for three straight years.
Teachers who already have tenure would lose it if their students do not show progress for two straight years.
(KUSA-TV © 2010 Multimedia Holdings Corporation with The Associated Press)