In plants, an expanded family of receptor kinases (RKs) transduce either ‘self’ or ‘non‐self’ signals into changes in nuclear gene expression. Plant RKs are typically characterized by an extracellular domain, a single transmembrane pass and in most cases, a functional intracellular kinase domain. Extracellular domains (ECDs) can modulate the activity of signaling competent RKs complexes by controlling ligand specificity and by recruiting appropriate signaling partners. Owing to the inherently transient nature of their interactions and bottlenecks with their expression in heterologous systems, there is very limited knowledge on the global interaction network ECDs can establish in their resting or ligand-activated functioning modes. I will present our genome-scale efforts aimed at discovering novel ECD interactions in the RKs repertoire of Arabidopsis. Finally, I will show how Genome Wide Association mapping studies can be used to decode systems-level determinants of specificity in receptor interaction networks.