This study employed a qualitative research design to investigate instructional designers' views and uses of conceptual tools in design work (e.g., learning theories and design theories). While past research has examined how instructional designers spend their time, how they generally make decisions, and expert-novice differences, little attention has been paid to the value and perceptions of conceptual tools, from the perspective of practicing designers. Based on intensive interviews of practitioners, our findings included ten themes organized according to three meta-themes: (a) using theory, (b) struggling with theory, and (c) connections between theory and intuition in craftwork. While these results substantiate (to some degree) the claim that practitioners often find theory too abstract or difficult to apply, they also suggest that practitioners use theory in several important ways and tend to view theory with ambivalence rather than indifference or dislike. Other conclusions regarding the role of theory in design are provided and future directions for theorizing and research are discussed.