STUDY DESIGN: Single-group repeated measures. OBJECTIVES: To adapt an existing arthrometer to allow simple quantification of glenohumeral translation and to assess the arthrometer's reliability. BACKGROUND: The measurement of glenohumeral translation is an integral part of the clinical examination of the shoulder. However, no objective and reliable measure for glenohumeral translation has been reported. METHODS AND MEASURES: The KT-1000 Knee Ligament Arthrometer was used to measure the amount of anterior-to-posterior (AP) translation of the humeral head at the glenohumeral joints of 28 (16 women and 12 men) nonimpaired undergraduate university students (age 22.1 +/- 2.9 years). Two assessments were made (20 minutes apart), by a single tester, of the dominant and nondominant shoulders of each participant. RESULTS: Anterior-to-posterior translation varied from 10 to 32 mm (20.9 +/- 4.9). The test-retest reliability of the KT-1000 when measuring the nondominant shoulders was good (ICC [intraclass correlation coefficient] 0.76), and it was moderate (ICC = 0.67) when measuring the dominant shoulders. The reliability findings were influenced by large amounts of random error. Analysis by ANOVA showed that compared to women (dominant shoulder, 22.6 +/- 4.6 mm; nondominant, 23.8 +/- 4.2 mm), men showed significantly less glenohumeral translation (dominant, 17.1 +/- 3.7 mm; nondominant, 18.3 +/- 3.7 mm). CONCLUSIONS: The KT-1000 arthrometer has the potential to provide therapists with a clinically viable method of measuring glenohumeral translation.