Researchers often deal with constructs that are conceptually and/or empirically related, but distinct (i.e., “sibling constructs”). In social-personality psychology, as well as psychology more generally, there is little guidance for how to deal with sibling constructs, which can result in researchers ignoring or mishandling them. In this paper, we start by situating sibling constructs in the literature on the jingle-jangle fallacies. Then, we outline 10 conceptual and empirical criteria for determining the degree to which, and in what ways, constructs may share a sibling relationship, using self-esteem and grandiose narcissism as a running example. Finally, we discuss strategies for handling sibling constructs in a systematic and transparent way. We hope that the procedures described here will help social-personality psychologists identify sibling constructs, understand when and why they pose problems for their research, and adopt strategies that ameliorate their adverse effects.