Synopsis The Lilavati of Bhaskaracarya (born A.D. 1114), the renowned astronomer of Bijappur in the Deccan, has, for more than eight centuries now continued to be the most popular text-book of mathematics among the students of Indian mathematics and astronomy. The all-India popularity of the work is apparent from its numerous manuscripts, inscribed in the different Indian scripts, found all over India and the more than hundred commentaries on it in Sanskrit and the other Indian regional languages. Of the above-mentioned commentaries, the Kriyakramakari, a joint production of two mathematicians of Kerala, Sankara and Narayana, of the 16th century, published here for the first time, is, perhaps, the most elaborate exposition of the Lilavati. The speciality of this commentary, which extends to about 500 pages in close print, lies in its endeavouring to analyse mathematical theories and to supply the rationale behind the numerous formulae set out in the Lilavati. Besides presenting a critical edition of the Kriyakramakari, with an informative Introduction, the publication carries five Appendices including a glossary of over 300 technical terms used in the Lilavati and its commentary, with their English exquivalents. It should be possible, with the help of this commentary, to get an insight into the working of the mind of the early Indian mathematicians and astronomers.