Abstract: A modular locking binder system is disclosed having a channel is coupled to the binder spine. The channel has an open end and a constricted region. A channel block is located at the open end of said channel and is configured to block and unlock the channel opening. The modular locking binder system is configured to removably hold a document module within the channel. The document module includes a module spine having a widened portion configured to operatively engage and be restrained by the constricted region of the channel. By either obstructing or un-obstructing the channel with the channel block, it is possible to removeably secure the document module within the channel when the widened ends of the document module are operatively engaged and restrained by the constricted portions of the channel.