The volume is the first outcome of an international project aiming towards a complete critical edition of the Kasikavrtti (7th c. CE) of Jayaditya and Vamana, the oldest surviving complete commentary on the Astadhyayi of Panini (ca. 4th c. BCE). The first phase, culminating in the critical edition of the Kasika’s initial section devoted to the Pratyaharasutras, the ‘rules for abbreviations’, was jointly coordinated by the editors together with Professor Saroja Bhate (Pune), a Paninian scholar of global renown. The first part of the volume presents the critical edition of the Pratyaharasutra section by Bhate, Haag and Vergiani, along with a description of the manuscripts collated, an annotated English translation by the editors, and the editors’ contributions dealing with the history of the Kasikavrtti’s editions and the currently available textual sources, as well as the methodology and results of the first phase of the project. In the second part, various authors discuss theoretical, historical and methodological topics ranging from the historical importance of the Kasika and its relation with the seminal Mahabhasya of Patanjali, to a comparison with the corresponding section in the Candavrtti, the evidence of Bhartrhari’s influence on the Kasika, and the copyists’ invocations and the incipit attested in the Kasikavrtti manuscripts.