This study investigates how familiarity and initial contact with species can be explained by social-demographic variables in an arid environment of Argentina. Our main objectives were to investigate which species children are familiar with, and analyse the effect of place of residence, sex and age on students’ knowledge and initial contact with species. In total, 1746 students between 7 and 18 years old participated in the study, from 25 urban and 19 rural schools. Students were asked to write down ten animals and ten plants, and to indicate where they had seen them for the first time. Children were able to name an important number of species but they were mostly acquainted with exotic ones. Familiarity with species and the use of different sources of information can be explained by interactions between the studied factors, while place of residence was not as significant as we expected. Sex was an important explanatory variable, likely influenced by differences in roles and children activities’ preferences. It is necessary to improve the knowledge on native species, particularly those with conservation problems by using information sources close to nature, without neglecting the knowledge of the exotic species that children showed more familiarity from everyday life.