People with cognitive impairments, such as older adults with dementia, can benefit from psychosocial interventions. Such interventions can be therapies or actions used to (re-)integrate a person into society and as of later years - robot companions have become one of the available tools. This doctoral thesis has investigated how robot companions for older adults living in care homes affects both the end users and the staff providing the psychosocial interventions. For older adults, a domestic pet robot can decrease worry, increase personhood by having something to care for, and even replace sedatives at times, while a humanoid robot might not be as accepted by this user group. For the staff, deployments of robotic welfare technology can lead to technostress and effective usage requires time and motivation, which, for example, decreased during the pandemic.