An adjustable all-terrain dolly system (100) having a chassis assembly (110) that includes a frame (120) which has a right-side rail (122), a left-side rail (124), a first-adjustable cross member (126) and a second-adjustable cross member (128), and a first-rolling assembly (160) to include a first-set of inline wheels (164) and a second-rolling assembly to include a second-set of inline wheels (174) and at least one adjustable-locking mechanism (180). The frame of the dolly system defines a load-supporting platform, and the platform has a length which is at least about twice the front-to-rear length of each of the two sets of wheels. Furthermore, each wheel of the dolly system has a peripheral surface which is shaped to engage the underlying surface at a substantially single point to enhance the maneuverability of the dolly.