Research exists about secondary school Response to Intervention (RTI) models, but little is known about the concerns of middle and high school teachers who are working together to implement RTI practices as a shared responsibility. The extensive body of documentation on RTI at the elementary level has not helped educators develop systematic RTI implementation practices across all levels (Ehren, 2013). The purpose of this quantitative study was to determine whether there were differences in practice concerns, if any among middle school and high school teachers' RTI practice concerns when measured by the Impact Stage of the Stages of Concern Questionnaire (SoCQ). The theory of planned behavior informed the framework for this research. A Snowball Sampling strategy was used to recruit a total of 31 general education teachers from a Northeastern USA County. Data from teacher's SoCQ were analyzed using ANOVA to investigate the differences in concerns, if any between middle school teachers in Grades 6-8 and high school teachers in Grades 9-12 about RTI practices. The results indicated no differences between 6-8 and 9-12 grade teacher concerns for all questions. Findings from this research may reinforce the importance of discussions about sharing RTI practice concerns between middle and high school teachers. Such conversations may foster more collaborative teacher working relationships which may lead to better implementation of the RTI initiative across grade levels for improved student learning outcomes.