The proposed health benefits, product freshness, and concern about antibiotic-resistant bacteria have bolstered sales of organic poultry products. However, outdoor requirements for organic poultry could increase exposure to bacteria, including Salmonella. The objective of this study was to assess the effects of prebiotics and probiotics in feed (experiment 1) and acidifying water treatments (experiment 2) on organic broiler performance and the presence of preslaughter Salmonella. In experiment 1, a prebiotic (MOS), 2 probiotics, and a control treatment were implemented. In experiment 2, raw apple cider vinegar, an organic acid blend, H(2)O(2), and a control treatment were incorporated into the watering systems. For both experiments, 300 one-day-old Cobb 500 male chicks were randomly assigned to treatment and pen. On d 21, birds were weighed and allocated at 13 per pen within each of the 5 housing locations providing pasture access at the West Virginia University Certified Organic Farm. Data collection occurred from d 21 to 49. On d 21, probiotic 1, the prebiotic, and the organic acid blend yielded the highest BW but demonstrated the same ending bird BW. However, birds provided probiotic 1 and the prebiotic were at least 86 and 72% less likely to be contaminated with Salmonella preslaughter. The lowest bird BW were achieved by birds provided H(2)O(2) throughout the study; however, these birds were at least 7% less likely to harbor Salmonella preslaughter compared with birds in the control treatment.