"Herding games" are mimicry games played by children in several East African pastoralist societies. This article presents an ethnographic account of the herding game among the Hamar agro-pastoralist people of Southwest Ethiopia, and reveals the dynamics by which children learn pastoral ecological knowledge from each other and socialise one another into pastoralist linguacultural practices. During the herding game, male children of various ages learn from each other the indigenous categorisation system for livestock individuation, and internalise important semantic distinctions in the domain of coat colours and patterns, by mapping the categories for livestock appearance on pebbles and shells. The game also allows children to learn and practise the communicative style used in human-animal interactions: this includes the Hamar system of address for cattle, animal directives and "bell-ideophones", which are crucial in a pastoral soundscape. The study demonstrates the importance of child agency in linguacultural socialisation. Herding games and children's play are an important context for horizontal learning in small-scale pastoralist societies and should be given more attention in cross-cultural studies on child socialisation.