The value of being able to adapt lies in the potential of an animal to navigate and thrive in an ever-changing environment. In order to survive, animals need to encode experiences molecularly and modulate their behavior to adverse or favorable conditions. Neuropeptides are a well-known, diverse class of molecular messengers that regulate neuronal activity synaptically and non-synaptically to modulate behavior. Neuropeptides and their receptors constitute a widespread signaling network, but how these networks are functionally organized and modulate behavior remains largely unexplored. The nematode C. elegans serves as an exceptional model organism for studying behavioral changes due to its compact nervous system and availability of extensive genetic tools. Its well-defined oxygen-sensing circuit aids in understanding the role of peptidergic communication in an experience-dependent manner. To probe the structure of the peptidergic network, we recently generated a genome-wide interaction map of peptide-receptor couples using reverse pharmacology and mapped the peptidergic signaling network in the C. elegans nervous system. Using a combination of genetic, molecular, and behavioral approaches, we are investigating the role of specific peptidergic neurons within the oxygen-sensing circuit in establishing different experience-dependent behavioral states. By testing loss-of-function mutants of neuropeptides and peptide receptors expressed in the circuit, we are also dissecting molecular pathways governing experience-dependent behavioral plasticity. This work not only expands our understanding of the molecular and cellular basis of experience-dependent plasticity but may also provide functional insights into the organization of the peptide signaling network.