A pilot study examined the relationship in daily life between companion animal guardianship (pet ownership) and peoples' laughter. The study divided participants (n = 95) into 4 mutually exclusive groups: dog owners, cat owners, people who owned both dogs and cats, and people who owned neither. For one day, participants recorded in "laughter" logs the frequency and source of their laughter and the presence of others when laughing. Dog owners and people who owned both dogs and cats reported laughing more frequently than cat owners, as did people who owned neither. The most frequent source of laughter was spontaneous laughter resulting from a situation. People who owned both dogs and cats reported most frequent spontaneous laughter resulting from an incident involving a pet. Dog owners reported less; cat owners, the least. Dog owners and people who owned both dogs and cats reported laughing more frequently in the presence of their pets than did cat owners. Findings suggest a complex relationship between pet ownership and laughter. Dogs may serve as friends with whom to laugh or their behaviors may provide a greater source of laughter.