An increasing number of modern families, especially those with younger children, own pets. The goal of this paper is to systematize the knowledge so far about the different roles of pets in the modern family and their significance for individual family members and the family as a whole. The pets’ role changes during different stages of the family life cycle and adapts to the needs of the family at a certain stage. This paper presents the specific roles of pets in different phases of the family life cycle and presents the results of research on the role of pets in children's development and in improving the social, mental and physical health of family members. Furthermore, the paper points out that owning pets can also lead to the appearance of some specific challenges and difficulties in the family, such as financial challenges, illnesses and injuries, intense grieving after the death of a pet. Attitude towards the pet can encourage the development of responsibility in children and the creation of a positive family climate and sense of unity. Equally, the attitude of family members towards a pet can be an indicator of various problems in the functioning of the family, for example violence against pets can be an indicator of the appearance of disorders in the behaviour and psychosocial functioning of children and young people and various other forms of violence within the family. In the final part of the paper, the possibility of integrating pets into the professional activity of social workers with families is described, aimed at preventing and identifying risks, strengthening protective factors and encouraging positive changes in the family.