Laboratory animal science is considered by many to be a contested enterprise. Yet the animal technicians working in the laboratory do not characterize their job as one consisting of insurmountable ethical dilemmas. Their job is to care for the animals and their welfare, as well as providing good conditions for research. This requires careful tinkering and negotiation between the disparate demands to find arrangements that work. And arrangements that work for the technicians are the ones where the tensions between disparate demands are not experienced to be colliding into ethical dilemmas. The aim of this thesis then, is to explore how the animal technicians make sense of the field of animal laboratory science and the research animals in order to understand how they deal with the tensions they encounter in their job.