This Festschrift was published in honor of Joshua Guttman on the occasion of his 66.66 birthday. The impact of his work is reflected in the 23 contributions enclosed in this volume. Joshua’s most influential and enduring contribution to the field has been the development of the strand space formalism for analyzing cryptographic protocols. It is one of several “symbolic approaches” to security protocol analysis in which the underlying details of cryptographic primitives are abstracted away, allowing a focus on potential flaws in the communication patterns between participants. His attention to the underlying logic of strand spaces has also allowed him to merge domain-specific reasoning about protocols with general purpose, first-order logical theories. The identification of clear principles in a domain paves the way to automated reasoning, and Joshua has been a leader in the development and distribution of several tools for security analysis.