The early Solvay conferences were remarkable occasions, made possible by the generosity of Belgian industrialist Ernest Solvay and, with the exception of the first conference in 1911, planned and organised by the indefatigable Hendrik Antoon Lorentz. In this chapter, we shall first sketch the beginnings of the Solvay conferences, Lorentz's involvement and the situation in the years leading up to 1927 (Sections 1.1 and 1.2). Then we shall describe specifically the planning of the fifth Solvay conference, both in its scientific aspects (Section 1.3) and in its more practical aspects (Section 1.4). Section 1.5 presents the day-by-day progress of the conference as far as it can be reconstructed from the sources, while Section 1.6 follows the making of the volume of proceedings, which is the main source of original material from the fifth Solvay conference and forms Part III of this book.