The purpose of this study was to identify the components of effective blended learning (BL) that administrators and teachers in a K-12 setting perceived as having the most significant impact on student achievement. The Commonwealth of Learning's (2018) Blended Course Learnability Evaluation Checklist was used as a framework to create an online survey distributed to all general education administrators and teachers at Valparaiso Community Schools in Northwest Indiana. Participants were asked to both rate and rank 6 general categories and 33 components of effective BL identified in the survey. The survey also included an opportunity for respondents to provide qualitative comments to support their choices and make any suggestions for components that were not identified in the survey. Descriptive statistics, Spearman rank correlation, and ANOVA were used to analyze the level of agreement between the respondents. Deeper analysis of the rankings was conducted among the two groups to explore the impact of demographics on perceptions. Rankings were disaggregated by: (a) building level; (b) years of experience; (c) grade level; and (d) subject area. Results from this study revealed that administrators and teachers rated all 33 components of BL to have "some impact," with the majority indicating "high impact" on student achievement. Analysis of the rankings indicated considerable agreement between the administrators and teachers regarding which components have the greatest impact. Results from the extended demographic analysis indicate that some components are perceived to impact student achievement differently, but most rankings indicate agreement among the sub-groups examined. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]