Teacher leadership has been widely studied by researchers aiming to understand teachers' roles in school improvement and professional learning. Researchers have determined that teacher leaders can work to increase professional learning and support school improvement. The first purpose of this study was to investigate the types of roles teacher leaders held and the types of work teacher leaders in elementary schools in a school district in Florida conducted during the COVID-19 Pandemic. The second purpose of this study was to estimate the association between the frequency with which teacher leaders conduct specific actions and student achievement levels. This study was conducted in a school district in Florida and included survey data from 34 teacher leaders in thirteen schools and student achievement data from the same thirteen schools. The association between the frequency with which teacher leaders conducted certain actions and student achievement levels was estimated using a multiple regression model, which used student demographic information as covariates. This study determined that most teacher leaders in the sample held at least one formal role and that they supported student achievement by supporting and collaborating with other teachers. Additionally, most teacher leaders reported that their work as a leader was altered due to the COVID-19 Pandemic. Results of the multiple regression analysis showed somewhat mixed patterns in terms of the associations between the frequency of different teacher leadership actions and student achievement scores in English language arts (ELA) and mathematics. The two leadership actions with positive associations with student achievement scores were allowing other teachers to observe teacher leaders and teacher leaders presenting or leading staff meetings. Several other teacher leadership actions were negatively associated with student achievement scores, including leading a team meeting or PLC for curriculum planning or data-based decision making, providing formal staff professional development sessions, observing other teachers' instruction, providing feedback to teachers after observations, discussing school policy with administrators, and attending a professional development session aimed at improving leadership skills. [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.]