We investigated how students' strategic knowledge about situational (pictorial) drawings and mathematical (schematic) drawings affects drawing accuracy and modeling competencies in the domain of geometry. We conducted a pre-posttest experimental study with 473 students in grade 9. Students were randomly assigned to one of three treatment conditions in which we used a 90-minute intervention to promote strategic knowledge about situational drawing (EG1), strategic knowledge about mathematical drawing (EG2), or strategic knowledge about situational and mathematical drawing (EG3). We also used a control group in which we did not promote any knowledge about drawing (CG). Results of a multilevel path analysis did not show a total effect of the strategic knowledge treatments on students' modeling competencies. However, the results indicated an indirect effect: Students who participated in the treatments demonstrated higher modeling competencies than students in the control condition, and strategic knowledge and drawing accuracy were mediating variables. Moreover, students who constructed a more accurate situational or mathematical drawing for a modeling problem were more likely to solve this problem adequately. Our findings indicate that strategic knowledge is a necessary but not sufficient precondition for the construction of high-quality drawings and high modeling competencies in geometry.