A helmet, comprising: a helmet shell; and a retention system (100, 220, 520, 600, 700) attached to the helmet shell, the retention system comprising a rear portion (102, 222, 602, 722) connected to the rear of the helmet shell, first and second straps (108, 230, 608A, 608B, 730) extending from the rear portion to a front portion (106, 606) of the helmet shell, and an adjustment device (114, 232, 614, 732) attached to the rear portion for adjusting the length of the first and second straps between the rear portion and the front portion of the helmet shell; wherein each of the first and second straps comprises a strap segment (110, 450, 452, 610A, 610B, 750, 752) and an elongated member (112, 240, 410, 412, 612, 710) attached to the strap segment, and wherein the elongated member is attached to both strap segments; wherein the adjustment device is configured to selectively adjust the elongated member to move the first and second strap segments relative to the helmet shell and adjust the length of the first and second straps between the rear portion and the front portion of the helmet shell to tighten and loosen the straps about the head of the user; and wherein the retention system further comprises; a chin portion configured to receive the chin of a person wearing the helmet; a pair of third straps extending from the chin portion to the rear portion, wherein the length of each third strap between the chin portion and the rear portion is selectively adjustable; and a pair of fourth straps extending from the chin portion to the right and left front portions of the helmet shell, wherein the length of each fourth strap between the chin portion and the front portions of the helmet is selectively adjustable. a helmet shell; and a retention system (100, 220, 520, 600, 700) attached to the helmet shell, the retention system comprising a rear portion (102, 222, 602, 722) connected to the rear of the helmet shell, first and second straps (108, 230, 608A, 608B, 730) extending from the rear portion to a front portion (106, 606) of the helmet shell, and an adjustment device (114, 232, 614, 732) attached to the rear portion for adjusting the length of the first and second straps between the rear portion and the front portion of the helmet shell; wherein each of the first and second straps comprises a strap segment (110, 450, 452, 610A, 610B, 750, 752) and an elongated member (112, 240, 410, 412, 612, 710) attached to the strap segment, and wherein the elongated member is attached to both strap segments; wherein the adjustment device is configured to selectively adjust the elongated member to move the first and second strap segments relative to the helmet shell and adjust the length of the first and second straps between the rear portion and the front portion of the helmet shell to tighten and loosen the straps about the head of the user; and wherein the retention system further comprises; a chin portion configured to receive the chin of a person wearing the helmet; a pair of third straps extending from the chin portion to the rear portion, wherein the length of each third strap between the chin portion and the rear portion is selectively adjustable; and a pair of fourth straps extending from the chin portion to the right and left front portions of the helmet shell, wherein the length of each fourth strap between the chin portion and the front portions of the helmet is selectively adjustable.