“In the beginning was the Word”, an old German lawyers’ adage has it, “but soon, it was followed by a Commentary”. The German legal tradition is peculiar in its reliance on article-by-article commentaries as authoritative guides to the law, but international law is catching up fast: from the Charter of the United Nations via the United Nations Convention on the Law of the Sea, human rights treaties and the agreements of the World Trade Organisation to the Statute of the International Court of Justice, a fast-growing patchwork of commentaries covers an ever larger part of the discipline‘s major texts. This growth attracts new players. While dedicated series by Oxford University Press and Hart/Beck/Nomos have so far been dominant, Edward Elgar has entered the field: its Practical Commentary to The ICSID Convention, Regulations and Rules, edited by Julien Fouret, Rémy Gerbay and Gloria M Alvarez (with Denis Parchajev), adds a genuine international law title to the Elgar Commentaries series. By all accounts and standards, this is an impressive book. On circa 1300 pages of text, it offers detail on the meaning of the 74 provisions of the International Convention on the Settlement of Investment Disputes (ICSID Convention), as well as (in more summarised form) the Administrative and Financial Regulations, the Institution Rules and the Arbitration Rules. The result is a compact, one-stop guide to the most relevant arbitral framework of investment arbitration.