Research Findings: A total of 54 videotaped mathematics activity observations drawn from 27 different pre-kindergarten classrooms in an urban public schools system in the U.S. were coded using 2 observational measures: (1) a general measure, the Classroom Assessment Scoring System (CLASS); and (2) a math-specific measure, the High Impact Strategies in Early Mathematics (HIS-EM). Criterion validity analysis revealed varying levels of convergent and discriminant patterns between the two tools. Indications of these results are twofold: (1) to some extend both tools document the similar aspects of quality of instruction (e.g., instructional support); and (2) a math-specific measure can be more sensitive to document the various levels of mathematics specific instructional support provided during teaching episodes (e.g., math representations, establishment of math learning communities). Results also indicated that the quality of mathematics instruction observed was revealed to be low to medium levels. Practice or Policy: Even though the CLASS may be a useful tool in terms of understanding overall instructional quality, as a subject-specific tool, the HIS-EM might offer a benefit of the multidimensional measure of mathematics teaching quality, which enables the researcher to pinpoint the kinds of strengths that teachers exhibited in math instruction and areas in need of improvement and may assist the field to better identify potential instructional areas to target with professional development.