No Child Left Behind (NCLB) cemented a standardized testing assessment culture in the United States but research has highlighted the inequities (Au, 2020; Dixon, 1978; Grodsky et al., 2008; Khan, 2020; Moses & Nanna, 2007), unreliability (Hunt et al., 2010; Pizmony-Levy & Green Saraisky, 2016) and negative impacts (Berryhill et al., 2009; Boardman & Woodruff, 2004; Jones et al., 1999; Pennycook, 2011; Urdan & Paris, 1994) associated with these tests. The Every Student Succeeds Act (ESSA) allowed states to shift from standardized tests and implement alternative assessments, yet not much research has investigated the use of system-wide alternative assessments for educational accountability. This nonexperimental cross-sectional descriptive quantitative study examines teacher perceptions of how ESSA has impacted locally developed assessments, focusing on their psychometric dependability in assessing student learning. To address the research objectives of this study, the following questions were investigated: 1) to what extent do teachers perceive system-wide alternative assessments to be valid and reliable and 2) to what extent do institutions implement practices that enhance the validity and reliability of system-wide alternative assessments. Teachers in a large suburban Virginia K-12 public school district were surveyed using closed-ended questions to examine perceptions of validity and reliability of system-wide alternative assessments and the institutional frameworks in place that enhance the validity and reliability of these assessments. Descriptive analyses were conducted to identify patterns in the collected data. Findings indicated that teachers find alternative assessments to be a valid and reliable means of assessing student learning outcomes, though they would prefer to have agency over the design of these assessments. The study also concluded that educational institutions implement practices that enhance reliability of these alternative assessments regarding implementation and assessment content, but that may impair reliability of scoring. Practical implications include a need for consistent teacher training in the implementation and scoring of system-wide alternative assessments. The research suggests that future studies should explore whether these system-wide alternative assessments equitably evaluate student learning outcomes and further analyze construct validity of each assessment type. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]