Chanting, an ancient ritual practiced in diverse cultures and traditions worldwide, has typically been employed for meditation, healing, self-awareness, and psychological growth. However, there is little understanding of the physiological and psychological benefits of chanting, and how vocalization might contribute to such effects. This study aimed to determine whether 12-minutes of group chanting, through vocal or silent repetition of the sound om, would reduce stress and anxiety, while increasing feelings of social connection, and whether vocal chanting would yield stronger effects. Thirty-four participants were randomly assigned to vocal or silent group chanting conditions. Saliva samples were collected before and after chanting to assess cortisol levels, while self-report measures included the State Trait Anxiety Inventory and the Adapted Self-Report Altruism Scale (including additional items on cross-cultural altruism). Following chanting, participants also provided a written description of their experiences. Both vocal and silent chanting resulted in significant decreases in cortisol levels and self-reported anxiety. The reduction in cortisol was similar for vocal and silent chanting, but self-reported anxiety decreased more following vocal chanting. Altruism scores increased following both vocal and silent chanting. However, there was no evidence of altruistic tendencies extending toward people from a culture other than one’s own. Results are discussed in relation to the phenomenology of chanting, and to current theory and evidence on the physiological and psychological effects of chanting and singing.