A portable infusion pump system (10; 110), comprising: (a) a pump device (12; 14; 114) configured to accept a disposable fluid cartridge, including: (i) a housing (26; 28; 124), (ii) a drive mechanism (48; 64; 92; 150) with a motor, and (iii) a controller (42; 60; 168) operatively coupled to the drive mechanism; and (b) a disposable fluid cartridge (16; 112) which may be operatively coupled to the housing of the pump device, including: (i) a collapsible reservoir (76; 126) having an interior volume surrounded by a flexible fluid tight membrane, the interior volume being in fluid communication with a reservoir inlet port, (ii) a substantially rigid shell disposed over the collapsible reservoir, forming a second interior volume between an outside surface of the collapsible reservoir and an inside surface of the substantially rigid shell with a vent inlet port in communication with the second interior volume, and (iii) a delivery mechanism (132; 142) including a bore (144; 220) within a delivery mechanism body of the delivery mechanism, a spool (156; 340) slidingly disposed in the bore forming a collapsible first volume (244; 344) which is configured to communicate with the reservoir inlet port and dispense port of the bore independent of the reservoir inlet port, and a vent second volume isolated from the collapsible first volume, the vent second volume configured to be moveable between a position that allows the vent inlet port to communicate with a vent outlet port and a position where the vent inlet port and vent outlet port are isolated from each other. (a) a pump device (12; 14; 114) configured to accept a disposable fluid cartridge, including: (i) a housing (26; 28; 124), (ii) a drive mechanism (48; 64; 92; 150) with a motor, and (iii) a controller (42; 60; 168) operatively coupled to the drive mechanism; and (i) a housing (26; 28; 124), (ii) a drive mechanism (48; 64; 92; 150) with a motor, and (iii) a controller (42; 60; 168) operatively coupled to the drive mechanism; and (b) a disposable fluid cartridge (16; 112) which may be operatively coupled to the housing of the pump device, including: (i) a collapsible reservoir (76; 126) having an interior volume surrounded by a flexible fluid tight membrane, the interior volume being in fluid communication with a reservoir inlet port, (ii) a substantially rigid shell disposed over the collapsible reservoir, forming a second interior volume between an outside surface of the collapsible reservoir and an inside surface of the substantially rigid shell with a vent inlet port in communication with the second interior volume, and (iii) a delivery mechanism (132; 142) including a bore (144; 220) within a delivery mechanism body of the delivery mechanism, a spool (156; 340) slidingly disposed in the bore forming a collapsible first volume (244; 344) which is configured to communicate with the reservoir inlet port and dispense port of the bore independent of the reservoir inlet port, and a vent second volume isolated from the collapsible first volume, the vent second volume configured to be moveable between a position that allows the vent inlet port to communicate with a vent outlet port and a position where the vent inlet port and vent outlet port are isolated from each other. (i) a collapsible reservoir (76; 126) having an interior volume surrounded by a flexible fluid tight membrane, the interior volume being in fluid communication with a reservoir inlet port, (ii) a substantially rigid shell disposed over the collapsible reservoir, forming a second interior volume between an outside surface of the collapsible reservoir and an inside surface of the substantially rigid shell with a vent inlet port in communication with the second interior volume, and (iii) a delivery mechanism (132; 142) including a bore (144; 220) within a delivery mechanism body of the delivery mechanism, a spool (156; 340) slidingly disposed in the bore forming a collapsible first volume (244; 344) which is configured to communicate with the reservoir inlet port and dispense port of the bore independent of the reservoir inlet port, and a vent second volume isolated from the collapsible first volume, the vent second volume configured to be moveable between a position that allows the vent inlet port to communicate with a vent outlet port and a position where the vent inlet port and vent outlet port are isolated from each other.