© Policy Press 2018. In-work benefits (IWBs) are important in 'making work pay' for many low-income families. We consider the adequacy of Family Income Supplement (FIS) for Irish lone parents transitioning from social protection to paid employment. Drawing on interviews with lone parents and with stakeholders, FIS enables some lone parents to meet basic needs and move towards financial independence, there were also difficulties, and many are financially better off remaining on social protection. There is a need, either for significant changes or for the introduction of an alternative IWB to meet the requirements of lone parents transitioning from social protection to ensure that they are not living in poverty.