The workbooks are for teens through young adults and parents/ caregivers of tweens ages 6-12. However, the person who encouraged me to publish these books is a 76 year old woman with a slew of invisible illnesses. "Truth be told, we all have Invisible Cosmic Zebras to take care of!" And she's right. Upon first look, the books may seem like they're for a younger group, but the concept of the collection is that people with chronic, invisible illnesses are all taking care of something. Think of every lovable thing you've ever had to take care of—It probably wasn't the same age as you are, right? These workbooks will inspire you to give love and attention to your invisible illnesses in a similar fashion (by imagining your invisible illness as an Invisible Cosmic Zebra that you have to take care of). No matter what your age, your inner child will love these books. I myself use the concepts in them every day.