- "Specializations: Receive early access to six Specializations, available at launch on Xbox LIVE, and use them, one at a time, to achieve higher ranks in your Spartan career. In addition to gaining access to new ranks, Specializations unlock new customization options."
- — EB Games Australia Halo 4 Limited Edition Page.
There are a total of 8 specializations, 2 of which were available at launch (Wetwork & Operator), the rest being unlocked later. Those who purchased the Halo 4 Limited Edition had access to all 8 at launch. However, an email sent on October 15, 2012 stated that Standard Edition Halo 4 owners who played the game while connected to Xbox LIVE by November 20, 2012 (two weeks after release) would receive early access as well. In "The Halo Bulletin: 1.9.13", 343 revealed the dates that the remaining specializations would be unlocked for all players: 1/21/2013 - Pioneer and Pathfinder, 1/28/2013 - Engineer and Stalker, 2/4/2013 - Rogue and Tracker. 
Each specialization offers 10 new levels to unlock. The first 9 levels unlock unique armor permutations, a weapon skin, foreground and background emblems, a visor, and eventually, at the 10th level, a Support Upgrade or a Tactical Package. Specializations can only be earned upon reaching SR-50.
"Spartan optimization for stealth operations which focus on the elimination of an enemy target with the goal of leaving no tactical footprint behind."
Completing all ten levels of the Wetwork specialization grants the user the Stealth Support Upgrade, which dampens the noise the user makes while sprinting and speeds up assassinations. Additionally, instead of showing up as a red figure when seen through Promethean Vision, a player using the Stealth mod will appear blue like other inanimate objects, and cannot be seen through walls and other solid objects. The Wetwork Specialization was made available at launch together with the Operator specialization.
"Spartan optimization for deployment into uncharted, hostile territory (such as uncolonized worlds or forerunner installations) for the purpose of gathering/relaying information."
The Fast Track Tactical Package earned by completing the Pioneer specialization earns extra experience when equipped, allowing players to rank up faster. However, you only gain extra XP for the time Fast Track was equipped in the match. Using a loadout with Fast Track equipped near the end of a match will not get you extra XP for actions performed earlier in the match. Assuming the perk is constantly equipped, Fast Track yields an XP bonus of about 20%. The Fast Track bonus is not affected by Double XP.
Pioneer-class armor was worn by Spartan-IV security escort detail during initial forays on Shield World Trevelyan and Installation 03.
"Spartan optimization for the subversion, repair, and/or reconstitution of a wide range of technology, including Covenant and Forerunner complex networks."
The Drop Recon Support Upgrade gives Spartan-IVs a crucial advantage in procuring ordnance. Ordnance will appear on the HUD of Spartans utilizing the Drop Recon armor mod at longer ranges. Additionally, incoming timed ordnance drops in the vicinity will show up on the user's HUD, informing the user about the location of the ordnance drop, the weapon dropped and time remaining before it drops.
"Spartan optimization for long range target tracking [trans-continent and off-world]. particularly in scenarios where conventional tracking has failed or such a substantial time has passed that the trail has gone cold." When players earn Personal Ordnance, they are offered three random choices - which may not always be desirable. However, players with the Requisition Tactical Package gain a fourth option; by pressing up on the D-pad, players effectively 're-roll', replacing the first set of three options with three randomly determined ones. Once 're-rolled', the effect is irreversible, and items may repeat (e.g. you may get an Overshield initially and after reselecting), but it greatly increases a player's chances of obtaining more desirable ordnance.
"Spartan optimization for single-operative missions which require a Spartan to be deployed on their own for incredibly long durations of time, even years if required."
Completing the Rogue specialization unlocks the Stability Support Upgrade which steadies your weapon while being struck by incoming fire, increasing the user's accuracy and lethality at longer ranges.
The stability support upgrade does not remove all shake from incoming fire, but the reduction in shake is still noteworthy.
"Spartan optimization for target shadowing missions which require tactical invisibility despite operating at an extremely close range to the target itself."
Stalkers gain access to the Nemesis Support Upgrade, a passive skill which creates an icon over the last person that killed you on your HUD lasting for four seconds after you respawn, allowing skilled users and coordinated teams to hunt down playmakers, objective carriers and power weapon holders.
"Spartan optimization for deep, unconventional deployment within unknown enemy territory and with little to no assistance from Command."
Pathfinders enjoy the Gunner Support Upgrade, which reduces the cool-down time on mounted weapons when overheating and allows those who use it to move at a normal walking pace while carrying a detached emplacement, greatly increasing the efficiency of detached turrets.
"Spartan optimization for the operation and control of a wide-range of vehicles, space, air, ground, and sea."
Completing the Operator specialization grants access to the Wheelman Tactical Package. Tailored towards heavy vehicle users, a Spartan with the Wheelman armor mod driving any vehicle enjoys significantly higher resistance to EMP shots - halving the duration the vehicle is stalled for from 4 seconds to 2 - and increases the durability of the vehicle by slightly increasing its health regeneration rate. In addition, vehicles driven by a Wheelman user are slightly more difficult to board.