This paper reports on the findings from the use of concept maps in a mathematics foundation course at a university in Kuwait. The study sample consisted of 130 freshmen students from a mathematics foundation course. Through a case-study design, concept maps and assessment tests were utilized to assess and monitor students' mathematical understanding and achievement at various points of the course. The findings of the study showed that concept maps can be effective as a tool to assess, monitor, and improve students' mathematical understanding, particularly their conceptual understanding when they are used systematically and when their use is followed-up by discussions that encourage students to reflect and talk about their maps and the links they have made. The improved understanding was found to contribute to the enhancement of mathematical achievement. The paper reports details on the use of concept maps in mathematics lessons and makes recommendations for practice and future research.