Language serves many functions for humans, but three of the most important are coordination, learning, and friendship. All of those functions were well served by the conversations from which this special issue emerged, a conference, "Grounding language in perception and (inter) action", held at Gordon College in June 2009. The conference brought together researchers primarily from three research traditions, dynamical systems theory, distributed language, and ecological psychology, and each of these perspectives is reviewed and illustrated in this special issue. The particular focus of this issue, though, is the role of conversations in humans caring for each other and the ecosystems of which they are a part. Emergency medical care, parents and children playing, and students learning a second language, are among the contexts of caring considered. Also considered are ways in which symbol systems emerge, ways in which language extends and alters perception-action systems, and ways in which infant-caregiver relations (i.e., first friendships) are constituted. The various articles explore how language is "situated, culturally embodied, emergent, and distributed" (Zukow-Goldring, this issue); how language is a crucial dimension of the extended phenotype of humans; how language increases our ability to care for each other, our common tasks, and the (real or virtual) ecosystems we inhabit; and how language emerges as we coordinate and share perception and action skills.