Abstract In the past 10 years a small number of articles have examined the personal and organizational costs associated with euthanasia-related strain among employees in animal shelters. However, there is very little research focusing on a wider range of potentialstressors especially without a pre-existing assumption that euthanasia is the most stressful part of the job. A few studies have identified other sources of stress among shelter workers. Therefore, the purpose of the present study is to investigate the range of factors that may contribute to occupational stress in shelter workers. This study utilized a semi-structured interview. The participants were 22 shelter employees from seven shelters in Ontario, Canada and the northeastern United States. Data were analyzed using the constant comparative method. Three categories of stressors were identified: a) those that are unique or largely unique to the shelter setting; b) those that can be found in a wide variety of occupations; and c) those that can be found in a wide variety of occupations, but are played out in unique ways in shelters. The stressors in the first category are reported here. Although euthanasia was a significant factor for 21 participants, five other major sources of stress were identified. Twenty-one participants cited the public’s perceptions of animal shelters and 18 cited rude and abusive human clients. Twelve cited relationships with the animals including attachment issues. Eight identified responsibility for life as a stressor. Eleven identified witnessing animal suffering.