The five papers in this issue cover a range of perspectives on the acquisition and use of the Spanish copulas "ser" and "estar" in a variety of contexts, including language contact, bilingual language acquisition, and classroom second language learning. The fact that these papers cite work in this area as far back as the early part of the 20th century with each subsequent decade being represented suggests the continual importance and complexity of the distinction between the two copular forms and shows how this complexity is played out in acquisition and bilingual use. Over the past century different perspectives have been taken on this multifaceted issue with linguistic explanations and the role of the native language being primary. In this epilogue, we focus on some of these same issues, but expand our commentary to include the new dimensions represented in this collection of papers: (i) context of learning (input), (ii) prior knowledge as represented by other language(s) known, (iii) item-learning and lexical development, and (iv) innovations in methodology.