Relationship quality is studied in a variety of disciplines, yet widely accepted practices promulgate a lack of conceptual clarity. We build on a conceptually simple and theoretically advantageous view of relationship quality and suggest a shift to conceptualizing it as two distinct yet related dimensions—positive and negative evaluations of relationships. We introduce item response theory as a powerful tool for measure development, demonstrating how relationship quality can be optimally pursued in the context of modern test theory, thus leading to better theory development. Recognizing the limitations of self-reported relationship quality, we extend this two-dimensional conceptualization further by drawing on developments in the derivation of implicit measures. After briefly introducing such measures, we illustrate their application to assessment of relationship quality.