From executive producer Jennifer Lopez, The Fosters is an ABC Family drama about the life of a multi-ethnic family of both foster and biological children, being raised by two mothers. Stef Foster is a mentally and physically strong, dedicated police officer who ended a previous marriage with her husband, Mike, to be with her partner, Lena Adams, who is the vice principal of Anchor Beach Community Charter School, where the kids attend. While with Mike, Stef has a son, Brandon, who continues to live with her, Lena, and their foster children: Mariana and Jesus, who are twins.

Right before the twins' fifteenth birthday, Lena surprises the entire family with another adoption, this time, a teenage girl, Callie Jacob, just released from Juvie. Since she previously lived in Juvie, many people, including Stef and Lena, feel that Callie could be a threat to the peace of their already extensive family. However, Callie is just a troubled girl struggling to recover from her dark past, living in and out of various foster families. Her most recent family, Jarett Moore who was an abusive foster father, is to blame for Callie being sent to Juvie because he claimed that she attacked him for no apparent reasons. Callie merely protected herself and Jude from his harm. The foster father reported Callie to the foster care agency and they took her away from Jude and into Juvie. When Callie is released from Juvie, warmhearted Lena decides to bring Callie home with her to meet Stef and the rest of the family. Initially, Callie is quick to judge their atypical family because Stef and Lena are same sex partners. Despite Callie's past, Stef agrees with Lena to keep Callie for the time being.