This study assessed the effects of different social environments (school vs. workplace), degrees of friendship (friends vs. acquaintances), and sociability levels (high vs. low) on on-the-job-training students’ likelihood of adopting different types of relationally aggressive behavior. By means of two questionnaires, on-the-job-training students from different universities in Manila were assigned to one of two sociability groups and assessed by their likelihood of adopting different types of relationally aggressive behavior in situations involving a friend or a simple acquaintance, occurring in school and in the workplace. Results revealed that: 1) individuals with low sociability are more likely to use backstabbing than individuals with high sociability; 2) social environment is an important factor in determining individuals’ likelihood of adopting specific relationally aggressive behaviors such as spreading rumors and silent treatment. However, these results were qualified by interactions with sociability and degree of friendship; and 3) no differences were observed concerning the excluding behavior. Results are discussed focusing on the findings’ practical applications.