This chapter treats the design considerations for dictionaries as printed books, the transition from print to digital formats in the thirty years around the turn of the twenty-first century, and the considerations for digital and online formats. Section 1: Customer-focused decisions about format, size, and extent of physical dictionaries; the mapping of book and page components of printed dictionaries; the mutual influence of editorial and design choices; and the advent of digital composition and production for printed formats. Section 2: Factors driving the choice of digital versus print formats for changing customer needs; functional challenges of converting printed dictionaries to digital; design considerations for online interfaces, including both technical performance and user experience.