A method of fabricating a composite assembly, including: laying up a plurality of first composite plies to form a first layup; laying up a plurality of second composite plies to form a second layup; curing the first and second layup in a manner forming a respective first and second laminate (206, 216) each having a respective first and second cured section (208, 218) and a respective first and second uncured section (210, 220); interleaving the first composite plies in the first uncured section with the second composite plies in the second uncured section to form an interfacial region; and curing the interfacial region to join the first laminate to the second laminate and form a unitized composite assembly; wherein the step of laying up the first and second composite plies and interleaving includes: inserting a ply separator between at least one pair of first composite plies and/or between at least one pair of second composite plies in a respective first and second uncured section (210, 220); at least partially curing the respective first and second uncured section (210, 220); preventing bonding of the respective first and second composite plies (204, 214) in the respective first and second uncured section (210, 220) as a result of the ply separator being inserted between the composite plies (204, 214); and removing the ply separator prior to interleaving the first and second composite plies (204, 214). laying up a plurality of first composite plies to form a first layup; laying up a plurality of second composite plies to form a second layup; curing the first and second layup in a manner forming a respective first and second laminate (206, 216) each having a respective first and second cured section (208, 218) and a respective first and second uncured section (210, 220); interleaving the first composite plies in the first uncured section with the second composite plies in the second uncured section to form an interfacial region; and curing the interfacial region to join the first laminate to the second laminate and form a unitized composite assembly; wherein the step of laying up the first and second composite plies and interleaving includes: inserting a ply separator between at least one pair of first composite plies and/or between at least one pair of second composite plies in a respective first and second uncured section (210, 220); at least partially curing the respective first and second uncured section (210, 220); preventing bonding of the respective first and second composite plies (204, 214) in the respective first and second uncured section (210, 220) as a result of the ply separator being inserted between the composite plies (204, 214); and removing the ply separator prior to interleaving the first and second composite plies (204, 214). inserting a ply separator between at least one pair of first composite plies and/or between at least one pair of second composite plies in a respective first and second uncured section (210, 220); at least partially curing the respective first and second uncured section (210, 220); preventing bonding of the respective first and second composite plies (204, 214) in the respective first and second uncured section (210, 220) as a result of the ply separator being inserted between the composite plies (204, 214); and removing the ply separator prior to interleaving the first and second composite plies (204, 214).