Persons with moderate to more severe intellectual disabilities have a legal right to exercise self-determination, and a right to receive individually tailored support to enable them to live independently. However, these rights are not always realised in practice. Taking the difficulties that the functional impairments imply as a starting point, the aim of this thesis is to critically review and accrue increased knowledge about what conditions for self-determination persons with moderate to more severe intellectual disabilities are given within the context of support services offered, according to the Swedish Disability Act. The study is a multiple case study, based on analyses of so-called implementation plans and notes from observations and interviews (with staff), all gathered within the same six units:three group homes and three daily activity units. By conducting thematic analyses and using concepts from Nordenfeldt’s action theory, as well as theory about positioning, three overarching themes were developed: staff’s supportive methods and approaches, staff’s non-supportive methods and approaches, and staff’s methods and approaches that are both supportive and not when it comes to opportunities for self-determination. For example, staff views on the persons’self-determination as being adequate are interpreted as supportive. As a contrast, the fact that enhanced support is rarely used and, if used, rarely to a degree that promotes the person’s own initiative, is interpreted as non-supportive, and the implementation plans are interpreted as both supportive and non-supportive. Fundamentally, the study shows that the practical possibilities to exercise self determinationare limited for persons with moderate to severe intellectual disabilities by certain aspects of staff methods and approaches, and by the organisation of the units where the support is conducted. Further research is suggested on how to enable practise, staff methods and approaches that, to a higher degree, consider the persons themselves when planning and conducting their support, on the organisational preconditions, the implementation plans included, for complying with the principles and political goals of a person’s self determination and on the impact of staff knowledge, not least when it comes to enhanced support and communication devices. Finally, the character of conducting support and what this means for the methods and approaches, should be investigated further.