O n 8 May 1902, searing gases and ash hurtled down the flanks of Mount Pelee on the Caribbean island of Martinique, killing all but two of the 28,000 inhabitants of St. Pierre. In seconds the nuees ardentes , or glowing clouds, of the massive pyroclastic flow transformed a vibrant town known as the Paris of the West Indies into a 20th century Pompeii. Ninety-five years later, another Caribbean town was wiped off the map, when pyroclastic flows from the Soufriere Hills volcano entombed Plymouth, the capital of Montserrat. But this time, no lives were lost: Plymouth had been evacuated. The volcano had given ample warning in a series of minor eruptions, and just as important, scientists had tuned in to subtler signals, including idiosyncratic patterns of seismic rumblings, which had given the volcano's game away. Volcanologists have made great strides in recent years in their ability to predict eruptions and to gird communities for the consequences. This Special Issue examines the state of the art of volcanology—and indeed, it is as much an art as a science, for volcanoes often defy predictions. Insights into their behavior and the ability to devise sound civil defense plans derive as much from intuition grounded in years of volcano-watching as from the latest code-breaking methods applied to the cryptic geophysical chatter that scientists eavesdrop on. Still, the balance is tilting in science's favor as new instruments and analytical approaches are brought to bear on restive volcanoes (see stories by Kerr, p. [2016][1], and Bachtold, p. 2026). And there are novel ways to collect data following an eruption: For the first time, scientists are drilling into the magma conduit of a recently active volcano, Unzen in Japan, to better understand why some eruptions are explosive (see story by Normile, p. [2018][2]). Volcanologists do not address such questions idly, of course, as their findings are often the basis for life-and-death decisions about how and when to evacuate communities. The experiences on Montserrat show how well risk assessments can work, even with the threat there rising as the volcano builds a gigantic lava dome (see story by Stone, p. [2027][3]). The stakes are also high in urban settings; thus scientists are keeping a tense vigil at Italy's Mount Vesuvius, which could threaten hundreds of thousands of people near its base if it were to awaken (see story by Bohannon, p. [2020][4]). It does not matter, however, how closely a volcano is watched if someone is in the wrong place at the wrong time during an eruption. Determining exactly how victims perish can lead to improved protection for volcanologists and others who must enter a danger zone and can even give them a shot at survival if caught in an eruption (see story by Stokstad, p. 2022). One big unknown on the health front is whether long-term exposure to ash and gases gives rise to chronic illnesses, a question now being tackled in earnest (see story by Pickrell, p. 2023). Working on an active volcano is not for the faint-hearted, especially in Africa and other regions where a dearth of basic equipment means that field expeditions—and putting one's life on the line—are the only way to gather data (see story by Krajick, p. [2024][5]). But as the stories in this Special Issue show, volcanology is a rewarding endeavor in which scientific advances are making rapid gains on intuition. Just ask the former residents of Plymouth. [1]: /lookup/doi/10.1126/science.299.5615.2016 [2]: /lookup/doi/10.1126/science.299.5615.2018 [3]: /lookup/doi/10.1126/science.299.5615.2027 [4]: /lookup/doi/10.1126/science.299.5615.2020 [5]: /lookup/doi/10.1126/science.299.5615.2024