The cover shows wrinkles on a surface-wrinkled adhesive that develop when it interfaces with a gelatin-based hydrogel. The material enables a moisture-controlled adhesion mechanism because of the dynamic changes in morphology that occur when the surface-wrinkled adhesive is exposed to water. These morphology changes alter the crack-pinning behavior as the wrinkled surface debonds from a substrate, controlling the adhesion. The approach is expected to be of use in biomedical applications, where adhesives need to work with moist and compliant materials such as soft tissues. Read the full story from Edwin Chan, Jeffrey Karp and Robert Langer on page 40 of this issue.