Accessible Summary An advocate helps you know your rights and what is expected of you. An advocate helps you speak up for yourself. Parents with learning disabilities need advocates when professionals are worried about their children. There is not much money for advocacy at the moment. Not all parents with learning disabilities can get advocacy. This is why we tried to find out if it makes sense for the government to spend more money on advocacy. We found out that advocacy can be good value for money. It can help parents and children. It can mean that social services have to pay less to help parents and their children. Summary Advocacy can help service users both to understand their rights and choices and also to support them in resolving issues of great significance to their lives. We investigated some of the costs and outcomes of advocacy provided to parents with learning disabilities at risk of having their children taken into care. Through two workshops and a survey, we gathered information about service use and outcomes at case‐ and project‐levels. We used evidence from previous studies to assign unit costs to service use and to value the economic consequences of outcomes. We combined data with simple decision‐modelling techniques. The mean cost of the advocacy intervention was £3040; potential cost savings per case ranged from £720 if we only considered the impact on children's social services, to over £3130 if savings to other public services were considered. Estimated improvements in quality of life and earnings were worth an additional £550. The limitations of our study mean those findings should be interpreted cautiously. Nonetheless, they suggest there is scope for securing better value for money through introducing advocacy for parents with learning disabilities.