Alloparental behaviors consist in a set of actions undertaken by adults to insure pups’ survival. Naive virgin mice can display alloparental behaviors the first time they are exposed to pups but their performances improve after a long or several exposures. The neurobiological substrates of this phenomenon are still unclear. This project aims to assess the role of olfaction in the establishment of alloparental behaviors and the ability of mice to recognize familiar from “alien” pups (ie pups never encountered before, with a different olfactory signature). We found that virgin mice display similar performances in a retrieval test as dams (ie mothers with litter) after being co-housed for several days with a dam and its litter. Their performances exceeded these of naive virgin females, as expected from the literature. Surprisingly, both dams and co-housed females retrieved their own and alien pups with a similar probability, suggesting an absence of discrimination. However, we found that dams and naive mice are in fact able to recognize alien pups when tested with a habituation-deshabituation test. These results suggest that even though mice discriminate pups from different origins, they retrieve them without distinction. In another set of experiments, we tested the impact of pups’ odor on another alloparental behavior: nesting. We showed that masking pups’ odor delayed the start of nesting in naive females, highlighting the role of olfaction in triggering this behavior when pups are present. This work paves the way for future research to understand how olfaction shapes pup-directed behavioral changes.