Since mathematics scores have not improved appreciably in the last 20 years, a need exists to improve fraction instruction for preservice teachers (PSTs), so future elementary students are more successful with fractions (NCES, 2019). Unfortunately, it appears that many future teachers have not mastered fractions to the point they can teach fractions without struggling or repeating the superficial approach their teachers used. How can one expect elementary students to master rational numbers and improve test scores when their teachers still need to improve their own understanding and skill? Educator preparation programs (EPPs) and faculty members have a significant opportunity to address and improve PSTs' fraction knowledge and thus their ability to teach rational numbers before they enter the classroom. Since fractions are so vital in school, STEM careers, and the real world, exploring improved fraction performance among PSTs may also benefit practicing teachers and students alike (Bruce et al., 2013; Gabriel, 2016). Thus, this integrative review of previous PST fraction research seeks to guide future studies and inform EPPs about the improvement of fraction mastery among future educators. The review was guided by the following research questions: (1) What has research revealed about PSTs' fraction knowledge and skill deficiencies? (2) What strategies may not be effective in helping one master fractions? and (3) What strategies and interventions improved PSTs fraction knowledge and performance?