The accurate and full title of the Kālacakra Tantra is Laghukālacakra Tantrarāja, Abridged Time Cycle, Tantra Monarch. The relevant sources maintain that the Abridged Kālacakra represents a shorter version of the root text (Mūlatantra), which is no longer extant.

The Kālacakra consists of five chapters, which are divided into three time-cycles: outer, inner, and other or alternative. Chapter 1 deals with the outer cycle, chapter 2 with the inner cycle, and the remaining three chapters with the alternative cycle. The outer and inner cycles of time encompass the inanimate and animate existence (saṃsāra), which evolves in conformity with the law of ethical retribution (karma). These two cycles are analogous and correspond to the outer universe or macrocosm and the human body or microcosm. The outer Kālacakra depicts the universe in terms of planetary constellations, astrological houses, and inner energies and permutations. The inner Kālacakra deals with the anatomy of the gross and subtle human body. The basic composition of the body consists of the five primary elements (earth, water, fire, wind, space) and consciousness. The innate character of consciousness or awareness is styled as luminosity or clear light (prabhāsvara). When stained by adventitious afflictions or defilements, this luminous awareness serves as the foundation from which the gross elements and the body emerge. In other words, when the forces of karma affect and flow together with the stream of consciousness, they determine the psychophysical composition of animate beings, and their passage through the outer cycle. Inside the gross body determined by the forces of karma, there flows the subtle body which consists of cosmic and psychic energies conceived as subtle channels, vital breaths and drops. It is this subtle body that constitutes the focus of the practices leading to its liberation from the forces of karma, and its enlightenment.

The alternative cycle of time essentially unfolds the path and practices that lead to the attainment of enlightenment. Chapter 3 provides an exposition of the Kālacakra initiations. Taken together, these initiations are bestowed as the spiritual foundation and seminal energy that sustain the ensuing practices. This chapter also explains the qualities of the Kālacakra master, the qualifications of disciples for receiving these initiations, and the maṇḍala in which the initiations are bestowed. It is a maṇḍala that reflects the perfect Kālacakra universe, which consists of luminosity emanated from the enlightened mind of the esoteric master acting as a Buddha.

Chapter 4 explains the stage of generation (upatti-krama) and the stage of completion (saṃpatti-krama). These two stages constitute two successive and integrated phases of the path of the highest Yoga Tantra. The stage of generation consists of the meditative visualization of the Kālacakra maṇḍala and its correlations to the outer and inner cycles. Kālacakra as the chief male deity is Time or phenomenal existence and nirvāṇa, but as he is free from all defilements, he is omniscient and unaffected by mundane time cycles. The different parts of his body, and indeed the entire maṇḍala, are identified with the Zodiac and other components of the outer universe, and with the vital energies and breaths flowing within the gross body. Conversely, the entire universe is styled as having the form of the maṇḍala. Succinctly stated, the generation stage entails the purification process of the psychophysical aggregates through engagement with the deities of the visualized maṇḍala. In terms of body, speech and mind, the three major aspects of a human being, once they are purified, the maṇḍala universe emerges as the body vajra, the deities form the speech vajra, and Kālacakra as the principal male deity epitomizes the mind vajra. Or again, when the five aggregates are purified, they are transmuted into the five cosmic Buddhas.

The completion stage consists of the six-fold yoga (ṣaḍaṅgayoga), which induces and culminates in the realization of the ultimate truth, combined with the realization of the great seal (mahāmudrā) or immutable knowledge. The six-fold yoga is also practised in other Buddhist schools, but in the Kālacakra system it is treated as the seminal and primary method for the attainment of the ultimate goal. The first limb of this yoga, retraction, consists in the withdrawal of the senses from their external objects, which results in stopping all external activities and viewing all phenomena in emptiness. During the second limb, absorption, the yogi meditates on the undifferentiated forms that appear in emptiness, in the sense that ultimately there are no beings or non-beings, because in emptiness the ultimate reality cannot be differentiated into polarities. The third limb, breath control, deals with the complex network of vital breaths (prāṇa) and their control. Ultimately, the variety of breaths is reduced to three: central, right and left. The principal goal of the next limb, retention, is the unification of the vital breaths with the subtle drop (bindu), and the meditation on the supreme and immutable knowledge. During the fifth limb, mindfulness, the enlightened mind (bodhicitta) melts, and descends in four phases from the head down to the tip of the vajra, while experiencing the four progressive grades of mystic joy. The final limb, samādhi, culminates with the attainment of the body and mind of a Buddha. The fifth chapter of the Kālacakra recapitulates the attainment of enlightenment through the above practices.

In the context of the above sketch of the Kālacakra Tantra, the present publication, the chapter on sādhanā, contains English translations of chapter 4 of this tantra and of Puṇḍarīka's seminal commentary on this chapter, the Vimalaprabhā. In addition to the Vimalaprabhā, Wallace provides numerous annotations based on Buston's commentary and some other sources.

As such the publication is divided into three parts. In Part 1 (Introduction), the author provides a helpful summary of chapter 4. Part 2 contains the English translations as explained above, and Part 3 offers a critical edition of the Mongolian version of chapter 4. The two appendixes respectively list the Sanskrit terms and the Sanskrit names of deities and persons occurring in the Mongolian version. This publication also provides a very comprehensive bibliography.

Viewed as a whole, this publication appertains to the top grade of scholarship and academic competence. The translation is accurate and elegant, and the annotations reflect the author's extensive research. It is a handsome contribution to the study of the Kālacakra system, although prospective readers must be warned that both chapter four and its commentary are not easy to comprehend. Just as the author suggests in her introduction, one needs to be acquainted with the outer and inner cycles of time before attempting to cope with the intricacies of this publication.