A wellbore completion system comprising: a tubular string disposed within a wellbore; an autofill and circulation assembly ACA incorporated within the tubular string and comprising: a housing generally defining an axial flowbore and comprising a first flow port and a second flow port extending between the axial flowbore and an exterior of the housing; and a first sleeve slidably positioned within the housing and transitional from a first longitudinal position to a second longitudinal position by sliding axially with respect to the housing and from the second longitudinal position to a third longitudinal position by sliding axially with respect to the housing; wherein, when the first sleeve is in the first position, the ACA is configured to allow a route of fluid communication from the exterior of the housing to the axial flowbore via the first flow port and to not allow a route of fluid communication from the axial flowbore to the exterior of the housing via the first flow port; wherein, when the first sleeve is in the second position, the ACA is configured to allow a bidirectional route of fluid communication between the exterior of the housing and the axial flowbore via the second flow port; and wherein, when the first sleeve is in the third position, the ACA is configured to disallow a route of fluid communication between the exterior of the housing and the axial flowbore. a tubular string disposed within a wellbore; an autofill and circulation assembly ACA incorporated within the tubular string and comprising: a housing generally defining an axial flowbore and comprising a first flow port and a second flow port extending between the axial flowbore and an exterior of the housing; and a first sleeve slidably positioned within the housing and transitional from a first longitudinal position to a second longitudinal position by sliding axially with respect to the housing and from the second longitudinal position to a third longitudinal position by sliding axially with respect to the housing; wherein, when the first sleeve is in the first position, the ACA is configured to allow a route of fluid communication from the exterior of the housing to the axial flowbore via the first flow port and to not allow a route of fluid communication from the axial flowbore to the exterior of the housing via the first flow port; wherein, when the first sleeve is in the second position, the ACA is configured to allow a bidirectional route of fluid communication between the exterior of the housing and the axial flowbore via the second flow port; and wherein, when the first sleeve is in the third position, the ACA is configured to disallow a route of fluid communication between the exterior of the housing and the axial flowbore. a housing generally defining an axial flowbore and comprising a first flow port and a second flow port extending between the axial flowbore and an exterior of the housing; and a first sleeve slidably positioned within the housing and transitional from a first longitudinal position to a second longitudinal position by sliding axially with respect to the housing and from the second longitudinal position to a third longitudinal position by sliding axially with respect to the housing; wherein, when the first sleeve is in the first position, the ACA is configured to allow a route of fluid communication from the exterior of the housing to the axial flowbore via the first flow port and to not allow a route of fluid communication from the axial flowbore to the exterior of the housing via the first flow port; wherein, when the first sleeve is in the second position, the ACA is configured to allow a bidirectional route of fluid communication between the exterior of the housing and the axial flowbore via the second flow port; and wherein, when the first sleeve is in the third position, the ACA is configured to disallow a route of fluid communication between the exterior of the housing and the axial flowbore.