Symposium BB, "Functional Nanowires and Nanotubes," was held November 27-December 2 at the 2011 MRS Fall Meeting in Boston, Massachusetts. Semiconductor nanowires are filamentary crystals with a diameter between several hundred and few nanometer. Both their size and morphology determine novel properties and provide room for novel applications. This symposium proceedings volume represents the recent advances in the area of nanowires. The contributions span all areas from the synthesis to the device, passing from the characterization of functional properties. Each paper in this volume provides a glimpse of the recent developments in the field such as: the use of nanowires for water splitting and hydrogen production and the use of nanowires as electrodes for lithium batteries.