In the past couple of years, a host of German monographs, based on doctoral theses, have examined the reigns of individual emperors during the third century crisis, for instance the books on Philippus Arabs by C. Körner (Philippus Arabs. Ein Soldatenkaiser in der Tradition des antoninisch-severischen Prinzipats [2002]), and on Valerian by T. Glas (Valerian. Kaisertum und Reformansätze in der Krisenphase des Römischen Reiches [2014]) to name but two noteworthy examples. Hitherto missing from this set of monographs was a study of the short-lived reign of Carus and his sons Carinus and Numerianus. The aim of A.’s book is twofold. It intends to replace earlier book-length studies, particularly P. Meloni (Il regno di Caro, Numeriano e Carino [1948]), by taking into account the latest historical research and offering a more exhaustive treatment. To this end A. provides a survey of the entire source material and an overview of the historical events in Chapters 3 and 4, and to some extent also in Chapter 5, which addresses more synchronic and systematic matters (pp. 185–318). The book's other aim is to investigate how far the joint rulership of Carus and his sons and, after his demise, that of Carinus and Numerianus can be considered a precursor to the Tetrarchy. A. discusses this topic in both the introduction (Chapter 1) and in the extensive Chapter 5, ‘Comparison between the Rulership of 282–285 and the Tetrarchy of Diocletian’. Unsurprisingly, he arrives at a rather fuzzy conclusion, for the Tetrarchy was the outcome of a transformation process that had already begun under the Severan dynasty and gained momentum during the crisis of the third century. It is therefore hardly possible to gauge the exact share of Carus and his sons in this development; if at all, their impact can most likely be discerned in the way they organised the imperial college, connecting territorial responsibilities to the order of imperial succession. It might possibly have been instrumental to single out the novel features of the Tetrarchy more systematically, presented in a separate chapter together with a review of current scholarship, in order to fully assess the potential role of Carus, Carinus and Numerianus as its precursors. The observation that under these three rulers there existed some kind of an upbeat spirit (‘Aufbruchstimmung’) which foreshadowed the subsequent reforms of the Tetrarchy hardly makes for a satisfactory conclusion. Perhaps a more elaborate discussion of particular sources could have produced more substantial results. For instance with regard to the partition of provinces, the dubious inscription on a bronze tablet (AE 1912.200) published by the future prime minister of Bulgaria, Bogdan Filow, merits a much more thorough analysis, apart from the fact that the Latin text is not rendered entirely correctly (p. 349 n. 46). Despite these criticisms, A.’s laborious effort has performed a useful service by providing a synthesis of all the issues relating to the emperors Carus, Carinus and Numerianus.