Forty-three quality initiatives use an observational tool. Of these, 36 (84%) use more than one tool. The Environment Rating Scales (ERS) are the most commonly used observational tools. Nearly three quarters of states use the ERS for some purpose, whether it be for the rating itself or for quality improvement (74%). The Classroom Assessment Scoring System is the second most commonly used tool. Just over half (51%) of states use the CLASS tool. Less than one-fourth (12%) of quality initiatives use self-developed or home-grown tools.