Abstract: A utility knife includes a hollow handle, for retractably housing a blade mounted on a blade carrier. The blade carrier is pivotally coupled to an actuator. A user can extend or retract the blade through a front slot by depressing an actuating button and sliding the actuator along an actuator glideway and blade carrier along a carrier glideway to a desired position. Once in the desired position a resilient member on the actuator urges protrusions on the actuator into engagement with detents provided within the handle. The blade carrier glideway is provided in an non-parallel orientation with respect to the actuator glideway to obtain a beneficial force transmission to the actuator that tends to maintain engagement between the actuator and the detents. A blade guard at least partially surrounds the front slot to resist upward forces on the: blade during cutting, while a carrier guard contacts a portion of the cutting edge of the blade within the handle to protect the carrier from damage by the blade.