In Kabbalah in Liturgy, Halakhah, and Custom, Moshe Hallamish asks the seminal question: From where does the kabbalist, whose sources are heavenly, or at best heard from a teacher, gain the ability to speak into the halakhic tradition (p.118)? Presumably, the principle of “lo ba-shamayim hi” should prevail, excluding any kind of kabbalistic privilege. He asks further, Is there a historical point where there is a sudden penetration or was it through progressive process? Does the Kabbalah create new forms to exert its influence or does it use the halakhic forms in existence? This collection of thirty-one articles is the most comprehensive attempt to assess the relationship between kabbalah and halakhah, prayer, and custom, and as such marks a significant milestone in this important area of research.