No political institutions enjoy less public trust than political parties. Understanding the implications of this phenomenon for representative democracy requires theoretically informed conceptualizations of party trust and distrust and theories about their underlying cognitive processes. In this vein, the present study conceptualizes party trust and distrust as perceived party trustworthiness, it models citizens' subjective standards as rubrics of party trustworthiness, and it derives rubric-based measures of party trust/distrust. The analyses identify rubrics that: (1) prize integrity and competence, (2) stress internal politics and competence, and (3) give priority to responsiveness and integrity. The rubric-based measures of party trust/distrust converge with a classic measure of party trust and, thus, bolster the conceptual validity and theoretical utility of this research. The results suggest new ways by which to measure party trust and distrust on public opinion surveys.