The volume is the first outcome of an international project aiming to create 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 this 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, a Paninian scholar of global renown. This edition is accompanied by a description of the manuscripts collated, an annotated English translation by the editors, and a series of editorial contributions dealing with the history of the Kasikavrtti's editions and its current textual sources. Summaries of the methodology and results of the project's first phase are also included. In the second part of the study, various authors discuss an array of 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 'Candravrtti', the evidence of Bhartrhari's influence on the Kasika, and the copyists' invocations and the incipit attested in the 'Kasikavrtti' manuscripts.