This chapter explores the evolving field of zoo animal welfare, beginning with a clear definition of what welfare means in the context of animals living in human care. It introduces the two principal frameworks used to assess and evaluate welfare: the Five Freedoms and the more contemporary Five Domains model, highlighting how each contributes to our understanding of animal welfare. Monitoring welfare in zoos is a highly complex and nuanced task. Unlike in laboratory or agricultural settings, zoos house a vast diversity of species, each with unique biological, behavioural, and psychological needs. This chapter delves into the practical challenges faced by zoo professionals, from interpreting subtle behavioural cues to managing the constraints of captive environments. It also examines how welfare assessments must be tailored to individual animals, taking into account factors such as age, health status, social dynamics, and even personality. With the rapid advancement of welfare science, zoos are increasingly equipped with the tools and knowledge to improve the lives of the animals they care for. Innovations in enrichment, enclosure design, and behavioural monitoring are helping to create more stimulating and supportive environments. However, these developments also raise a critical and ongoing question: Can the welfare needs of zoo animals ever be fully met? This chapter encourages you to think about that question for yourselves, weighing up how far we’ve come and what tricky issues still lie ahead.