As CUIs become more prevalent in both academic research and the commercial market, it becomes more essential to design usable and adoptable CUIs. Though research on the usability and design of CUIs has been growing greatly over the past decade, we see that many usability issues are still prevalent in current conversational voice interfaces, from issues in feedback and visibility, to learnability, to error correction, and more. These issues still exist in the most current conversational interfaces in the commercial market, like the Google Assistant, Amazon Alexa, and Siri. The aim of this workshop therefore is to bring both academics and industry practitioners together to bridge the gaps of knowledge in regards to the tools, practices, and methods used in the design of CUIs. This workshop will bring together both the research performed by academics in the field, and the practical experience and needs from industry practitioners, in order to have deeper discussions about the resources that require more research and development, in order to build better and more usable CUIs.