Care and service trajectories are identifiable routes through service systems that consist of all steps that people with intellectual disabilities (ID) and their families have to take to realize the care and services they need. Trajectories are especially prominent during the transitions from children's services to adult services. Within a service system in Noord-Brabant (in the Netherlands), the authors examined the course of such trajectories and their main bottlenecks and sought to identify their quality determinants. The first research question was addressed by an exercise in document analysis and the holding of semistructured interviews with key informants within the healthcare sector specialized for serving people with ID. A second research question was addressed by means of a literature review on integrated care. The authors observe that trajectories generally follow a “model route” consisting of five phases but may vary according to age category, degree of disability, and life domain. With respect to “bottlenecks,” the authors noted that a lack of suitable supply and long waiting lists are good examples. They found that the literature on integrated care revealed that continuity, accessibility, availability, and flexibility of care and services, together with the seamlessness of transitions, are all important quality determinants for people with ID when judging their service trajectories. Bottlenecks and quality determinants of trajectories are strongly interrelated. The authors concluded that the literature and the key informants agree as to which factors are most important in realizing high-quality trajectories for individual clients. They recommend asking which criteria people with ID and their families value most when judging the quality of trajectories.