BACKGROUND: The older adult population is increasing in number, and elder abuse is expected to become a more pressing problem. Developing tools to assess the presence and severity of elder abuse is important to both effectively prevent this abuse and provide increased support for families. PURPOSE: This study was intended to test the validity of an Assessment Tool for Domestic Elder Abuse (ATDEA). The items that constitute this tool were derived from a literature review. METHODS: Two rounds of self-administered questionnaire surveys were conducted with nurses working at home-visit nursing stations. Round 1 was used to evaluate the face validity, and Round 2 was used to test the content using the content validity index (CVI). RESULTS: Two hundred forty nurses participated in the two studies. In Round 1, 56 nurses evaluated 38 items derived from a literature review, resulting in the development of a 36-item ATDEA. In Round 2, 184 nurses evaluated the content validity of the 36-item ATDEA. The Item-CVI (I-CVI) scores ranged from .61 to 1. Twenty-eight of the items met or exceeded the I-CVI threshold of .78, whereas the eight items assessing self-neglect did not. The overall Scale-CVI score for the assessment tool was .90, which met the threshold of .90. CONCLUSIONS/IMPLICATIONS FOR PRACTICE: The results of validity testing established the preliminary validity of this assessment tool. In addition, as self-neglect is known to damage the well-being of older adults, six of the eight items assessing self-neglect were retained in the ATDEA despite their failure to meet the threshold I-CVI of .78. The remaining two self-neglect items were not included in the ATDEA because of excessively low I-CVI scores (< .70). Thus, the final version of the ATDEA includes 34 items. The authors recommend that nursing professionals use the ATDEA as a checklist to assess the presence of elder abuse and to discern the subtypes and severity of this abuse. When evaluating elder abuse, the higher the degree of severity, the greater the urgency to provide support.