Syncrisis is the process of making item-level comparisons between two or more people. It was proposed as a method for more directly assessing the amount of similarity between inventory respondents than standard scoring technology allows (e.g., correlation between profiles, and D('2) measures of similarity). Three experiments were conducted. Experiment 1 was a three week long test-retest reliability study. Two structured inventories, the Jackson Personality Inventory (JPI) and the Kuder Occupational Interest Survey (KOIS), were used as the bases for syncritically formed interpersonal similarity matrices on the test and retest data. The median reliability for syncritic scoring of the JPI was .78, while the median reliability of the KOIS was .87. There were no sex differences. Experiment 2 was an attempt to relate similarity indices (syncritic and profile-based) of a group clients compared to six therapists, to clients' preferences for individual counselors. No similarity measure was significantly related to clients' self-reported preferences for therapists. Experiment 3 was an exploratory client-therapist matching study. Syncritically-based similarity between clients and counselors (graduate students) was significantly correlated with the supervisor's grade of the therapists' performances. Profile-based similarity measures were not positively correlated with either outcome measure (therapists' grades, clients' ratings of their therapist). The discussion concludes that syncrisis was found to be adequately reliable for research and applied uses. Further validity studies were suggested and outlined.