Learning by drawing can be an effective strategy for supporting science text comprehension. However, drawing can also be cognitively demanding and time consuming, and students may not create quality drawings without sufficient guidance. Furthermore, evidence for drawing is often based on comparisons to weak control conditions, such as students who only read the text without provided illustrations. In this review, we synthesize past research to help draw boundary conditions for learning by drawing, focusing on the role of comparison conditions and drawing guidance. First, we analyze how drawing compares to each of four control conditions: reading only, text-focused strategies (e.g., summarizing), other model-focused strategies (e.g., imagining), or viewing instructor-provided illustrations. Next, we distinguish among four levels of drawing guidance: minimal guidance, drawing training, partially provided illustrations, and comparison to instructor-provided illustrations. Our findings indicate that when compared to only reading the text or using text-focused strategies, creating drawings is consistently more effective at fostering comprehension and transfer, regardless of the level of drawing guidance provided. However, when compared to other model-focused strategies or to viewing instructor-provided illustrations, effects of creating drawings are mixed and may depend on the level of drawing guidance provided, among other factors. We discuss the theoretical and practical considerations of our findings and suggest several directions for broadening research on drawing.