Literature suggests that "current characterizations of the terms procedural knowledge and conceptual knowledge are limiting and are, in fact, impediments to careful investigation of these constructs" (Star, 2005, p. 405). We examined secondary mathematics teachers' understanding of procedural and conceptual knowledge at superficial and deep levels through the design of mathematical tasks. For this purpose, N=55 secondary mathematics teachers were asked to design a procedural and a conceptual task on a given topic and explain why they think the task they designed is a procedural and/or conceptual task. The study results showed that 78% of teachers were able to design and correctly explain procedural tasks. However, only 5.5% of teachers were able to design conceptual tasks correctly. Teachers' narratives were examined to categorize emerging characteristics of procedural and conceptual tasks as well as to address teachers' (mis)conceptions about procedural and conceptual knowledge.