While the focus of positive psychology is uncontestably on the positive, there is an emerging direction in the field indicating that the coexistence of both negative and positive emotions is critical to well-being. The act of writing a condolence letter is a good example of precisely this coexistence: loss and sorrow giving rise to the act of expressive writing to convey positive emotions of sympathy, solace, and more. Viewed through the lens of positive psychology, writing a condolence letter has the potential to activate a unique alchemy of elements that the science of positive psychology has identified with well-being, from calling to action over inaction, meaning over despair, and resilience over hopelessness; to identifying character strengths and virtues and enhancing social bonds and generativity; to practicing the master virtue of practical wisdom in modulating the letter’s message to the context; and more. A review of condolence letters written over modern history illustrates how these elements have been used over the past two millennia. As there is little relevant empirical research on the impact of engaging in the practice of writing condolence letters on well-being, further study is in order, particularly given the challenges of Covid-19. For now, the practice of writing condolence letters would appear to offer numerous and unexpected opportunities to give rise to positive outcomes associated with increased well-being. This, in turn, enriches the support for the coexistence of the negative and the positive in a life well-lived in the science of positive psychology.