The quality of life experienced by social and healthcare professionals is among the factors that contribute to the definition of quality of service. Other factors seemingly in relation with experienced quality of life concern one's own efficacy, beliefs, and burnout. The present study intended to verify the relations that existed between these variables and the relation between professionals' characteristics and those of the users who benefited from their professional interventions. Involved were 146 social and healthcare professionals and 68 adults with intellectual disabilities. Concerning the influence of length of service, the analyses determined that significant increments exist in emotional exhaustion and depersonalization. There were increments, albeit not generalized, also with respect to self-efficacy. Satisfaction did not actually increase over time. Results from a discriminant functional analysis showed that only confidence in one's own ability to work in a team and establish productive and collaborative relationships with colleagues and superiors was a significant predictor of quality-of-life status. Further, the social and healthcare professionals who had higher levels of confidence in their own professional abilities cared for the individuals who showed greater self-determination, higher quality of life, and social skills.