John Locke did not write an ‘essay’ on the standard humanist topic of friendship; yet his letters, notebooks, and major works contain significant reflections on it, if not a systematic position. This article considers what Locke thought about the importance of conversation, often paired in humanist writings with the ideal of a perfect friendship between two equals. He entertained a version of this notion, asserting that best friends must be lovers of truth, but also valued informal exchanges with strangers as sources of new information and ideas. For Locke, conversation with both friends and strangers was a necessary instrument in the pursuit of truth.