To investigate the scope and nature of discrimination and positive treatment experienced by adults with mental health problems from their friends and family in a population-based survey.An Australian telephone-survey of 5220 adults included 1381 individuals who reported a mental health problem or scored high on a screening questionnaire. Respondents were interviewed about their experience of discrimination and positive treatment from their friends, spouse and other family members. Descriptions of experiences were content-analysed to identify key characteristics.Mental health diagnoses were primarily depression or anxiety disorders, and just over half had received treatment in the last 12 months. Positive treatment from family and friends was far more common than discrimination, reported by 74.1% of respondents. This was primarily characterised by providing emotional support and maintaining contact, as well as checking on their mental health and being a good listener. Nevertheless, discriminatory behaviours from friends and family were reported by 25.8% of respondents, with reducing or cutting contact being by far the most common. Friends and family also commonly dismissed that mental illness was real or caused suffering and showed a lack of understanding about mental health problems or treatments and how they can impact behaviour and functioning.This nationally representative study of real life experiences highlights the potential for harm or benefit from a person's social support network. Despite positive experiences being common, there is an ongoing need to reduce mental illness stigma and improve understanding of how to support a loved one with a mental health problem.