Whether you are a zookeeper, veterinarian, volunteer, or visitor, your presence in a zoo has an impact on the animals, and that impact might be positive, negative, or neutral. Every interaction, no matter how brief or passive, contributes to the complex web of human-animal relationships that shapes the daily experiences of zoo-housed animals. This chapter explores how these relationships form, what influences them, and most importantly, how we can ensure that our presence supports animal welfare rather than undermines it. Scientific research into human-animal interactions has shown that animals respond to people in diverse ways, depending on factors such as species, individual temperament, enclosure design, and the nature of the interaction. For example, small, arboreal primates may be more sensitive to human presence than larger, ground-dwelling species, and animals with a history of positive, predictable interactions with humans are more likely to respond calmly or even seek out engagement. Alternatively, unpredictable or stressful encounters can lead to animals showing fear and avoidance, contributing to negative welfare outcomes. By understanding these dynamics, we can begin to tailor our behaviour and zoo environments to foster positive human-animal relationships. This chapter will guide you through the science behind these interactions, drawing on recent studies of both primate and non-primate species. It will highlight practical strategies for minimising stress and maximising enrichment, whether you’re caring for animals behind the scenes or simply observing them from the visitor path.