The main purpose of this paper was to work, within the framework of construct validity theory, toward the delineation of a construct of reasoning. In so doing, we address reasoning, broadly conceived. We make no claim to have considered every aspect of this complex construct. The outcome of our deliberations is a list of elements that, we believe, are useful to consider in any attempt to specify the facets of a construct of reasoning ability. As we note, befitting such an important construct, there have been many attempts to articulate its (multifaceted) nature, some of which are discussed here. Given the variety of ways in which reasoning has been characterized, however, we offer no single definition or comprehensive vision of reasoning. Rather, we attempt only to set forth some of the salient features of reasoning that, to us, seem worthy of consideration and possibly of incorporation in any construct statement of reasoning. Our main conclusion is that there is no single construct of reasoning. Instead, any of several formulations may be equally useful and informative depending on the particular context and the user's purpose. We hope, though, that our reflections provide some of the "grist" that users may need in order to specify a construct of reasoning that meets their requirements.