Evidence suggests that experienced instructional designers often use heuristics and adapted models when engaged in the instructional design problem-solving process. This study used the Delphi technique to identify a core set of heuristics designers reported as being important to the success of the design process. The overarching purpose of the study was: (1) to examine and describe the heuristics that guided instructional designers' practice and (2) to identify the relationship between these heuristics and key competencies of the discipline, as outlined by the International Board of Standards for Training, Performance, and Instruction. Sixty-one heuristics were ultimately identified (reached consensus). All 61 aligned with at least one of the four categories of IBSTPI, with some aligning with more than one. More specifically, 17 heuristics aligned with Professional Foundations competencies, 17 aligned with Planning and Analysis competencies, 18 aligned with Design and Development competencies and 10 aligned with Implementation and Management competencies. By examining instructional design heuristics, we hope to better understand the potential genesis and/or future application of each heuristic. Results provide insights into the specific heuristics experienced designers perceive as being effective during the ID process. (Contains 3 tables.)