A quantitative methodology was used to analyze Illinois elementary principals' survey responses to determine if there was a relationship between certain principals' values, frequency of evidence-based practices, and other principal characteristics and the student achievement after accounting for the socio-economic status (SES) of the schools. Specifically, this research examined the commonalities in principal values, the frequency of their evidence-based practices, and/or principal characteristics. Elementary principals who work in schools with varying socioeconomic levels were identified in order to determine which practices were most important in schools with high levels of poverty. Elementary principals in Illinois schools (excluding Chicago and the pilot principal schools) were surveyed in order to get representation from various categories of schools. By sorting the principals' schools into four different levels of SES, any relationships between variables were compared between the schools with varying degrees of SES and the school's combined achievement on the PARCC assessment. Several key findings came out of this study. This survey research found a correlation between several of the valued evidence-based practices and the frequency principals reported engaging in these practices. Two evidence-based practices that principals reported engaging in showed a statistically significant relationship after accounting for the socioeconomic status (SES) of the school, specifically in high achieving, low-SES schools. In addition, although this research study found significant relationships between several principal characteristics and evidence-based practices, the findings did not yield practical implications for superintendents who hire principals, because the differences between the values and frequency of engagement of the principals were not distinct. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]