One of the major challenges faced in modern synthetic chemistry is the efficient and selective assembly of complex molecular structures, especially carbo- and heterocycles, from readily accessible starting materials. With this has arisen the development of tandem reaction processes, which permit multiple transformations in a single synthetic step and that have often provided elegant routes to complex target scaffolds from simple precursors. Propargyl alcohols and their derivatives have become increasingly attractive starting materials for such processes owing to their reactivity in the presence of a Brønsted or Lewis acid catalyst as well as halogenation reagents. This account describes our recent efforts in the field, and demonstrates how propargyl alcohols and their derivatives can be transformed into a diverse range of highly functionalized acyclic, carbocyclic and heterocyclic structures, which are of importance as synthetic building blocks and as motifs in functional materials and bioactive compounds. 1 Introduction 2 Acyclic Conjugated Enynes 3 Carbocycles 3.1 Indenes 3.2 Dihydrofluorenes 3.3 Cyclopentenes, Cyclobutenes and Cyclopenta[b]naphthalenes 3.4 ortho-Phenolic Esters 4 Heterocycles with One Heteroatom 4.1 Indoles 4.2 Piperidines, Azepines and Pyrrolidines 4.3 Pyrroles 4.4 Furans 4.5 Benzo[b]oxepines and Benzo[b]azepines 5 Heterocycles with Two Heteroatoms 5.1 Thiazoles and Oxazoles 5.2 Dioxolanes 6 Conclusion