The controlling theme of Missing May is grief and the grieving process. Grief is the natural reaction to loss; it is a universal experience encountered many times throughout a person's life. May's death was a physical, or tangible, loss for Ob and Summer. According to Summer, "all Ob and me wanted to do when we lost May was hold onto each other and wail in that trailer for days and days." They weren't able to do that because "there are certain ways people expect you to grieve." Summer and Ob had a funeral ritual for May and acted "proper" in front of relatives and people they didn't even know. After the funeral, Ob and Summer began the grieving process in their own way and time.
One way to understand the grieving process is to view it as tasks or stages that people move through after they have experienced a loss. At first, they must accept the reality of the loss. To deal with the loss, people might choose isolation or denial. Both Summer and Ob chose denial. Summer denied her feelings related to May's death and absence.
She attempted to fill May's shoes. The responsibility of taking care of Ob kept her occupied, so she didn't have to deal with her feelings about the loss of May. After May died, Ob denied that she was really gone. He felt her presence and believed she was with them.
The next task or stage has to do with experiencing the pain or grief. Summer did not experience the pain of May's death until the night they returned home from their journey to Putnam County. She saw an owl and was reminded of May. Summer cried until "[her] body was emptied of those tears and [she] was [no longer] burdened." Ob experienced the pain of May's death by becoming depressed. He didn't feel he had a reason to live without May. He struggled to get out of bed each day and one day he didn't even get dressed; he stayed in his pajamas. After Summer and Ob experienced their grief, they were able to accept May's death and look forward to adjusting to life without May.
In the characters of Ob and Summer, Rylant portrays the anguish and despair that people experience as a result of loss due to death. Rylant makes it clear that grieving is unique to each individual, the length of time each person grieves varies greatly, and hope and understanding enable people to be able to move on with their lives.
Another important theme in Missing May is the importance of family. Rylant suggests that a family does not have to include a biological mother, father, and children to be a family. She portrays unconventional families — families that are not traditional. One family that is unconventional is Summer's family. She lives with her elderly Aunt May (until she dies) and Uncle Ob. This is a perfect family for Summer: She feels safe, secure, and loved. Cletus' family is also unconventional. Although his parents are elderly people, Cletus also feels safe, secure, and loved. Rylant portrays the "darker" side of family life when she writes about a dysfunctional family — a family that includes conflict and poor relationships among family members. An example of a dysfunctional family is Summer's extended family in Ohio. After her mother died, her aunts and uncles didn't want her. They "treated [her] like a homework assignment somebody was always having to do."
Valuing the differences in others is another significant theme of Missing May. When Cletus began to visit Ob, Summer considered him to be a lunatic. It wasn't until she observed the way that he listened to and empathized with Ob that her opinion of Cletus changed. She realized he had "gifts." Summer was also a victim of people making incorrect assumptions about her. Her teacher asked the class to write descriptions of each other. Someone wrote a description about Summer that made her sound "like some sad welfare case, in the sorry way her clothes and hair were described." Summer's reaction was an urge to run home to Ob and May where she knew she would be safe. May was a good role model for Summer. May naturally thought the best of everyone and everything. She never judged anyone or anything. She "always liked the weird ones best." Summer was sure May would have liked Cletus. May even saw the beauty in bats; she treated them gently and lovingly.
Rylant hopes that by exposing her readers to grief as a natural reaction to loss resulting from death, the importance of family, and the uniqueness and value of every individual, she can bring awareness to her readers and thereby change perceptions and, ultimately, the society in which we live.