- Animal welfare is an essential component of agricultural production and animal use in teaching and research. However, defining animal welfare is intrinsically difficult because of how history and societal values and perceptions have shaped the term. Animal welfare encompasses three main ideas: physical well-being, normal affective/emotional states, and the ability for the animal to properly function in its environment even while stressors are present. Dairy cattle welfare assessment programs strive to evaluate farms based on these criteria. Assessment programs guide farmers in providing the highest standard of care by ensuring that on-farm animal welfare standards are met. Despite this, current animal welfare programs present limitations. Traditionally welfare evaluations might only occur every 1-3 years, even though animal welfare should be addressed more frequently. Furthermore, many programs evaluate different items on farm and this makes determining which assessments provide more accurate evaluations challenging. These welfare programs were not developed to take advantage of automatic sensor systems and/or do not allow to evaluate grazing cows. The latter is positively associated with higher welfare by consumers but a clear connection between grazing and welfare is still missing. Thus, there is a need to develop an integrated welfare monitoring tool for dairy farming systems across the globe (i.e. confined, grazing) that enables farmers to apply regular monitoring of the welfare status of cows to management routines. Furthermore, there is the need to develop a system to evaluate welfare in grazing cows. To satisfy the above need, the Integrated Diagnostic System Welfare (IDSW) was developed in Italy in the 1990’s. The current version (unpublished) is the Integrated Diagnostic systEm for dAiry cow weLfare (IDEAL). Objective 1 was to translate, update, and redesign the IDEAL to accommodate the needs of US dairy farmers. Because the IDEAL did not include grazing, Objective 2 was to develop and validate a model for the IDEAL that evaluated the welfare of grazing dairy cows. Objective 3 was to compare the welfare conditions of non-grazing and grazing cows by using a set of blood parameter, hair cortisol, and visual assessments of animals. We hypothesized that the IDEAL would capture a truer state of welfare on farms and that grazing cows would have a poor metabolic profile than non-grazing cows, compromising the welfare status. This hypothesis was created with previous data in mind. For the purpose, six dairy farms in Oregon were enrolled and assessed between March 15 – June 25, 2018. Four farms were visited twice, once during the non-grazing period and once during the grazing period and two farms were only visited once. Blood and hair samples were collected from a total of 145 dry, early lactation (30-50 days in milk), and late lactation cows (>200 days in milk). The number of lactations ranged from 2-7. Collected data were used for two studies: Study 1 to accomplish Objectives 1 and 2 and Study 2 to accomplish Objective 3. For Study 1, we successfully developed the IDEAL for US farms and created a component to evaluate grazing. When validating the IDEAL, comparing the non-grazing and grazing farms, we found no differences (P=0.20) between any of the evaluations scores. The one exception was for functionality of the digestive system (cows chewing cud) which scored higher in grazing periods. The blood analysis was used to directly assess the welfare of the animals. Blood parameter results were compared with available normal blood parameter ranges for each stage of lactation. A score was given to each parameter based of how far from normal it was. Scores for each blood parameters were acceptable for each farm and, except for a few parameters, no differences were observed between grazing and non-grazing cows. These data are consistent with the lack of difference in the IDEAL scores between grazing and non-grazing cows, indicating that IDEAL captures the real welfare of the animals. Despite this, IDEAL has many limitations that might have affected the final farm score. Furthermore, the low variability between assessed farms for the IDEAL scores was a limitation to validate the IDEAL. For Study 2, we detected differences in metabolic, immune-related, and inflammatory parameters suggesting that grazing cows having a better metabolic and immune situation. Thus, contrary to our hypothesis of this study, the data obtained indicated that grazing conditions provided a more animal welfare friendly environment for dairy cows. Lower hair cortisol further supported this conclusion. Overall, in our study we successfully developed an alpha version and performed a preliminary validation of the IDEAL on grazing and non-grazing US dairy farms. Our data support a better welfare status in grazing compared to non-grazing cows.