Ma Joad continually expresses the idea that there is strength in family. One clear example of this is in Chapter 16 when Tom suggests that he and Jim Casy stay behind to get the truck fixed while the others go on. Ma steadfastly refuses to go with out Tom. She says that the family is all that they have left in the world and she doesn't want to break it up. Another example is in Chapter 18 when Ma reveals that Granma had died before the group crossed the desert, but rather than reveal that and jeopardize the family's chances of making it across the desert to their destination in California, she lied at the border station and held Granma's body all night long. Many times Ma tells Tom that it is important that the family stay together each time expressing the idea that they only have each other.
Tom expresses his realization of the need for the family to work together, too, when he curbs his anger so that he won't get in trouble and be sent away. This happens in the first squatter's camp in Chapter 20 and again later, before entering the Hooper farm to pick peaches in Chapter 26. Later, in that same chapter, Tom has to be hidden because of the incriminating injury to his face. Ma again expresses the attitude that as long as the family is together, they can face any problem.