Despite benefits of family focused practice, little is known about health visitor's practice with families when mothers are mentally unwell. Health visitors are midwives and nurses with additional training in community public health. To explore multiple perspectives of health visitor's family focused practice with families when mothers have mental illness in Northern Ireland. Ten health visitors, 11 mothers with mental illness and seven partners completed in-depth interviews in Five Health and Social Care Trusts. Participants were asked to describe their experiences of providing or receiving family focused practice within health visiting and data was analysed using thematic analysis. Health visitors primarily addressed mothers and children's needs rather than also supporting partners. Additionally, they only addressed mother's needs associated with less severe mental illness (i.e. postnatal depression). Health visitors and mothers converged on many issues, including the influence of the health visitor's personal and professional experiences on their practice, central role of the relationship between health visitors and mothers and importance of health visitors supporting partner's well-being. While partners did not perceive that health visitors should support their well-being they expressed a need for further information and knowledge in order to support mothers. Health visitor's practice largely centres around mother and baby. For health visitors to increase their family focused practice they need to meet needs of mothers who have serious mental illness more effectively and consider how partners can be included in their practice, in a manner that is beneficial and acceptable to them. This study contributes to better understanding of health visitor's family focused practice with mentally ill mothers and highlights the need for more effective engagement with mothers with serious mental illness and partners. It also highlights that for health visitors to engage in family focused practice they need the necessary training and time to do so. Results can inform organisational developments in family focused practice within health visiting.