Mathematics scores on the 2019 National Assessment of Education Progress increased by only two points for both fourth and eighth grade students since 2007, indicating that students continue to struggle in mathematics (National Center for Educational Statistics, 2007; U.S. Department of Education, 2019). The development of both conceptual and procedural knowledge is crucial to student success, as such, it is imperative that educators remain informed of past and current research in conceptual and procedural knowledge so they may make important instructional decisions regarding the focus and sequence of instruction. This research employed a quantitative content analysis to analyze and describe the extent to which mathematics instruction that emphasizes conceptual knowledge, procedural knowledge, both conceptual and procedural knowledge, progression from conceptual to procedural knowledge, and progression from procedural to conceptual knowledge in mathematics have been positioned within the publications of the Journal for Research in Mathematics Education (JRME) and Educational Studies in Mathematics (ESM) research journals. Results indicate that research pertaining to conceptual and procedural knowledge remained consistent from 1988 to 2020, focusing mostly on conceptual knowledge development, incorporating constructivist practices that require students to make connections, notice patterns and relationships, and explain their thinking. The second most common focus was on developing both conceptual and procedural knowledge, incorporating both behaviorist and constructivist practices. [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.]