Actions, Bonus Actions, and Reactions Rules
The action economy in Dungeons & Dragons 5th Edition governs what a character can accomplish on a single turn, dividing available choices into three distinct categories: actions, bonus actions, and reactions. Each category carries different triggering conditions, availability rules, and interaction constraints that shape every round of combat. Mastery of these distinctions is foundational to understanding the D&D core rules overview and the broader combat rules framework.
Definition and scope
Action refers to the primary activity a creature performs on its turn. The Player's Handbook (5th Edition, Wizards of the Coast) defines the action as the main unit of turn economy, encompassing activities such as attacking, casting a spell with a casting time of "1 action," dashing, disengaging, dodging, helping, hiding, readying, searching, and using an object. Each creature receives exactly 1 action per turn unless a class feature or rule explicitly grants additional actions (e.g., the Fighter's Action Surge, which grants 1 additional action once per short or long rest).
Bonus action is a supplemental activity available only when a specific rule, class feature, spell, or ability grants it. The bonus action is not freely available — a creature that has no feature granting a bonus action on a given turn simply cannot take one. Common sources include the Rogue's Cunning Action, the two-weapon fighting rules (when attacking with a light weapon in the main hand), and spells with a casting time of "1 bonus action."
Reaction is an instantaneous response triggered by a specific event, either on the creature's own turn or on another creature's turn. A creature gets exactly 1 reaction per round, resetting at the start of its own turn. The most frequently cited reaction is the opportunity attack, triggered when a hostile creature moves out of reach. Spells such as Shield and Counterspell also use the reaction slot.
The scope of this framework applies to all creatures — player characters, non-player characters, and monsters — under the standard 5th Edition ruleset. Variant rules and optional mechanics from sources such as Tasha's Cauldron of Everything or the 2024 revised Player's Handbook (Wizards of the Coast, 2024) may adjust specific applications but do not alter the three-category structure.
How it works
Turn structure in 5th Edition proceeds in the following sequence:
- Start of turn — Any effects that trigger "at the start of your turn" resolve (e.g., ongoing damage from certain conditions).
- Movement — Up to the creature's full speed, which may be split before and after the action.
- Action — The creature selects from available action options (Attack, Cast a Spell, Dash, Disengage, Dodge, Help, Hide, Ready, Search, Use an Object, or a class/feature-specific action).
- Bonus action — If a qualifying rule grants one, the creature may take it before, during, or after the action (order is flexible unless the rule specifies otherwise).
- End of turn — Effects that trigger "at the end of your turn" resolve.
Reactions may occur at any point during the round — on the creature's own turn or another's — whenever the stated trigger condition is met.
A critical mechanical constraint governs spellcasting: when a creature casts a spell using a bonus action, it may only cast a cantrip with its action on that same turn (Player's Handbook, Chapter 10, "Casting Time"). This rule — often called the "bonus action spellcasting restriction" — is among the most frequently misapplied rules at tables. It does not restrict non-spell actions.
Common scenarios
Opportunity attacks represent the prototypical reaction. When a hostile creature voluntarily leaves a creature's reach without using the Disengage action, the threatened creature may expend its reaction to make one melee weapon attack. This intersects directly with movement and positioning rules and strategic decisions around the Disengage action.
Two-weapon fighting illustrates the action/bonus action split: the Attack action is used for the main-hand weapon; the off-hand attack requires the bonus action. Both weapons must have the light property unless the character has the Dual Wielder feat (Player's Handbook, Chapter 5, "Equipment"). See also equipment and weapons rules.
Cunning Action (Rogue, level 2) grants the ability to use a bonus action to Dash, Disengage, or Hide — a routine part of Rogue combat flow that interacts with stealth and hiding rules.
Counterspell (Xanathar's Guide to Everything, also Player's Handbook) uses a reaction triggered by observing a creature within 60 feet casting a spell. The caster must have their reaction available; once used, no further reactions are available until the start of the caster's next turn.
Ready action converts the action slot into a conditional future action: the creature declares an action and a trigger, then holds the action as a reaction until the trigger occurs or the turn ends. This is one of the few mechanisms that allows an action to be executed on another creature's turn.
Decision boundaries
The primary decision boundary separating these three categories is trigger requirement:
| Category | Availability | Trigger Required | Frequency |
|---|---|---|---|
| Action | Every turn | No | 1 per turn (typically) |
| Bonus Action | Only when granted by a rule | No external trigger; requires qualifying rule | 1 per turn (when available) |
| Reaction | Every round | Yes — specific stated trigger | 1 per round |
A second boundary concerns stacking: no rule permits a creature to take 2 bonus actions in one turn or 2 reactions in one round under standard 5th Edition rules, regardless of how many qualifying features the creature possesses. Action Surge is the only core mechanism granting an additional action, and it applies once per short or long rest at standard Fighter progression.
A third boundary involves spell interaction: bonus action spells and action spells interact asymmetrically. Casting a spell as a bonus action imposes the cantrip-only restriction on the action slot for that turn, but casting a spell as an action imposes no restriction on bonus action use. This asymmetry frequently arises in high-level play where characters manage spell slots and spell levels alongside spellcasting rules.
Understanding where these boundaries apply — particularly in edge cases involving conditions rules, grappling and shoving rules, and optional and variant rules — requires consulting the specific feature text rather than generalizing from the base definitions. The how recreation works conceptual overview provides broader context on how structured rule systems like this one operate within tabletop gaming as a recreational form. The full index of rule categories is accessible at the site index.
References
- Player's Handbook, 5th Edition — Wizards of the Coast (Chapter 9: Combat; Chapter 10: Spellcasting)
- Tasha's Cauldron of Everything — Wizards of the Coast
- Xanathar's Guide to Everything — Wizards of the Coast
- D&D Beyond Rules Compendium — Wizards of the Coast / Fandom
- Player's Handbook, 2024 Revised Edition — Wizards of the Coast