The influence of partner instrumentality for a single goal on the evaluation of the relationship constructs of satisfaction, investment size, quality of alternatives, and commitment was explored in two studies. The review of the literature frames these studies within the relative lack of information on evaluations in ongoing relationships and the importance of specific metrics for both theoretical and applied relationship science. Both studies utilized longitudinal data from couples (in Study 1) or individuals (Study 2) currently involved in a dating relationship to test the validity of a theoretical argument on the importance of partner instrumentality for a single goal and, more broadly, specific metrics. Additionally, the motivation to assess or evaluate the relationship was tested as a moderator of that influence. Results indicated partial support for the hypothesized positions, such that partner instrumentality for a single goal was positively related to evaluations of satisfaction with and commitment to the relationship over time, but was not related to evaluations of investment in or alternatives to the relationship. Furthermore, the use of transactional structural equation models in Study 2 allowed for the examination of the influence of a change in partner instrumentality on relationship evaluations, which confirmed that such changes influenced changes in satisfaction with and commitment to the relationship over the same time period. Certain findings were qualified by moderating effects of the motivation to assess the relationship (only in Study 2) and of gender (in both Study 1 and Study 2). Meaningful patterns of findings are discussed prior to detailing limitations and the need for future studies. Finally, conclusions and implications are reviewed.