Spider silk is an impressive material; lightweight and stretchy yet stronger than steel. But the challenge that spiders face to produce this substance is even more formidable. Silk proteins, called spidroins, must convert from a soluble form to solid fibers at ambient temperatures, with water as a solvent, and at high speed. How do spiders achieve this astounding feat? In new research publishing in the open access journal PLOS Biology on August 5, Anna Rising and Jan Johansson show how the silk formation process is regulated. The work was done at the Swedish University of Agricultural Sciences (SLU) and Karolinska Institutet in collaboration with colleagues in Latvia, China and USA.