The investigators seek to conduct the first open-label trial of probiotics in young children to reduce their anxiety and abdominal pain. Likewise, the investigators aim to assess the feasibility and efficacy of this treatment and to elucidate the enteric microbiota in the middle-lower GI tract. Self-report measures and a laboratory task will be collected from children, ages 9-13 years of age, and self-report measures from their primary caregivers prior to and following a 30-day probiotic administration. Children who score above cutoff in anxiety and/or abdominal pain meet the inclusion criteria for this study. Because of limited sample size and the iterative nature of intervention development, criteria for success at the pilot phase are based primarily on clinical rather than statistical criteria. The study personnel will do their best to keep and ensure the privacy and confidentiality of our participants; however, some of the risks of this study may include psychological discomfort, legal risks, and loss of confidentially.