A quadracycle is a four-wheeled human-powered land vehicle. It is also referred to as a quadricycle, quadcycle pedal car or four-wheeled bicycle, amongst other terms.

Human-powered quadracyles have been in use since 1853 and have grown into several families of vehicles for a variety of purposes, including tourist rentals, pedal taxis, private touring, mountain and industrial use.

There is no consensus amongst manufacturers of four-wheeled, human powered vehicles as to what this class of vehicles should be called, although quadracycle is the most commonly-used term. Manufacturers who do refer to their products by class of vehicle call them:

As well there are single manufacturers who call them Go-kart, Car, Car-Bike, Ecological car, Human Powered Vehicle, Pedal Kart, Quadribent, Quattrocycle, Surrey and Twin bike

The earliest recorded pedal-powered quadracycle was exhibited in 1853 at the Exhibition of the Industry of All Nations World's Fair held in New York City. This was about the same time that two-wheeled bicycles started to become popular. Quadracycles were one solution to the problem of low-speed stability in early cycles and were typically multi-seat models. Both tandem (in line) and sociable (side-by-side) seating configurations were used.