Abstract Background: Despite the rise in the occurrence of skin cancer, primary care nurse practitioners are reluctant to perform skin cancer assessments during patient visits. Melanoma is almost always curable if detected in the early stages, but invasive disease accounts for 9,000 deaths per year (American Cancer Society, 2013). Changing knowledge, attitudes and practice regarding skin cancer assessments potentially leads to early detection and treatment of skin cancers and impacts patient outcomes. However, in order to change knowledge and attitudes, we must first assess them. Purpose: The purpose of this research was to validate a new skin cancer assessment tool instrument called KAP-SCA to measure knowledge, attitude, and practice in primary care NPs. Methods: Sequential mixed methods were used. First, focus group interviews with 14 primary care nurse practitioners were conducted during Phase I. Interviews were audio-recorded then transcribed verbatim and imported into ATLAS.ti. Phase II involved instrument development from a blueprint and calculation of content validity indexes (CVI) for items and subscales. Phase III of this study included testing the validity and reliability of a KAP instrument using quantitative methods. This new instrument assesses primary care nurse practitioner knowledge, attitudes, and practice regarding skin cancer assessment. Results: Content validity for the subscales was evaluated by CVI ranged from .90 to .95. The Cronbach's alpha was highest for the practice subscale (alpha =.89) while the lowest was seen with the knowledge subscales (alpha =.50). Construct validity assessed by exploratory factor analysis indicated the presence of three underlying factors, confidence in practice, confidence relating to education and NP role in practice. Implications for Practice: Interventions need to be developed based on the knowledge deficits and barriers to practice identified by these NPs including educational programs that focus on increasing primary care NPs' knowledge and confidence levels regarding skin cancer assessments and identification of malignant lesions. Conclusion: Beginning evidence of validity and reliability were found for the Knowledge, Attitudes and Practice-Skin Cancer Assessments (KAP-SCA), however further studies are warranted.