---
title: "Accidental — AP Music Theory Definition & Notation Rules"
description: "An accidental is a sharp, flat, or natural sign that alters a pitch, written to the left of the notehead. Master placement rules and key signature contrasts for AP Music Theory."
canonical: "https://fiveable.me/ap-music-theory/key-terms/accidental"
type: "key-term"
subject: "AP Music Theory"
unit: "Unit 1"
---

# Accidental — AP Music Theory Definition & Notation Rules

## Definition

In AP Music Theory, an accidental is a symbol (sharp, flat, or natural) that modifies a notated pitch by raising it, lowering it, or canceling a previous alteration. Per the CED, an accidental is always drawn to the left of the notehead it affects (PIT-1.A.1).

## What It Is

An accidental is a notation symbol that changes a [pitch](/ap-music-theory/big-ideas/pitch/study-guide/ntesBiOItGszLn2CKCNS "fv-autolink") from what the [staff](/ap-music-theory/key-terms/staff "fv-autolink") position alone would tell you. A **sharp (♯)** raises a pitch by a half step, a **flat (♭)** lowers it by a half step, and a **natural (♮)** cancels a previous sharp or flat and restores the letter-name pitch. The CED is picky about one detail that trips people up on notation FRQs: the accidental goes to the **left of the notehead**, even though when you say the note out loud you put it after the letter ("B-flat").

[Accidentals](/ap-music-theory/unit-7/tonicization-through-secondary-dominant-chords/study-guide/rLCBduMA9EmMPYSSNiwd "fv-autolink") are how written music gets pitches that aren't covered by the clef and key signature. The staff and clef give you the seven letter names; accidentals fill in everything between them. That's also why one sound can have two spellings. F♯ and G♭ are the same key on the piano but different accidentals on the page, which is the whole idea behind enharmonic equivalents.

## Why It Matters

Accidentals live in **[Unit 1](/ap-music-theory/unit-1 "fv-autolink"): Music Fundamentals I**, specifically **Topic 1.1: Pitch and Pitch Notation**, supporting learning objective **[AP Music Theory](/ap-music-theory "fv-autolink") 1.1.A** (identify pitches on the staff in performed and notated music). Essential knowledge **PIT-1.A.1** names accidentals as the way pitch is "further distinguished" beyond staff position and spells out the left-of-the-notehead rule. But this is one of those Unit 1 ideas you never stop using. Every dictation answer you write, every error-detection question comparing score to performance (**1.1.B**), and every sight-singing melody (**1.1.C**) depends on reading and writing accidentals correctly. If you misread one accidental, you've misread the pitch, and on this exam pitch accuracy is the whole game.

## Connections

### [Enharmonic equivalent (Unit 1)](/ap-music-theory/key-terms/enharmonic-equivalent)

Two different accidentals can spell the exact same sound, like C♯ and D♭. Enharmonic equivalence only exists because accidentals exist, and the exam expects you to recognize when two spellings name one pitch.

### Key signatures (Unit 1)

A [key signature](/ap-music-theory/key-terms/key-signature "fv-autolink") is basically a batch of accidentals applied to the whole piece up front. Once you see that connection, accidentals within a measure read as exceptions to the key, which is exactly how you'll spot chromatic notes later.

### Clef and staff (Unit 1)

The [clef](/ap-music-theory/key-terms/clef "fv-autolink") assigns letter names to the lines and spaces, and the accidental fine-tunes that letter name up or down. You need both pieces to identify a pitch, which is the core skill in 1.1.A across treble, bass, alto, and tenor clefs.

### Sight-singing and dictation FRQs (Units 1+)

On sight-singing FRQs you have to perform accidentals accurately, and on [dictation](/ap-music-theory/unit-4/harmony-voice-leading-i/study-guide/0m8OiGeqjebWSd6bMZ0W "fv-autolink") FRQs (like harmonic dictation) you have to notate them correctly, including drawing them on the correct side of the notehead. Accidentals are a Unit 1 concept that gets graded all the way through the free-response section.

## On the AP Exam

Multiple-choice questions test accidentals directly with stems like "What does a sharp symbol indicate?" or "Where should accidentals be placed relative to the notehead?" Know all three answers cold. A sharp raises by a half step, a flat lowers by a half step, a natural cancels, and all of them sit to the left of the notehead. On the free-response side, accidentals show up everywhere you write or sing notation. Harmonic dictation questions (like 2024 FRQ 3) and the SAQ dictation items require you to notate any chromatic pitches with correct accidentals, and the sight-singing FRQs require you to perform them in tune. A missing or wrongly placed accidental is a pitch error, plain and simple.

## accidental vs Key signature

A key signature appears once at the start of each staff line and applies its sharps or flats to every octave for the whole piece. An accidental appears next to a single notehead and, by convention, applies only within that measure. Think of the key signature as the default settings and accidentals as one-off overrides. On notation questions, don't write an accidental for a note the key signature already covers.

## Key Takeaways

- An accidental is a sharp, flat, or natural sign that raises, lowers, or restores a pitch, as defined in PIT-1.A.1.
- Accidentals are always drawn to the left of the notehead, even though you say the letter name first when speaking ("B-flat").
- A natural sign cancels a previous sharp or flat and returns the note to its unaltered letter-name pitch.
- A key signature applies to the whole piece, while an accidental applies to a specific note within its measure.
- Different accidentals can spell the same sound (C♯ = D♭), which is what enharmonic equivalence means.
- Accidentals matter on FRQs too, since dictation answers need correctly placed accidentals and sight-singing requires you to perform them accurately.

## FAQs

### What is an accidental in AP Music Theory?

An accidental is a symbol that modifies a notated pitch. A sharp raises it a half step, a flat lowers it a half step, and a natural cancels a previous alteration. The CED (PIT-1.A.1) specifies it's drawn to the left of the notehead.

### Does an accidental apply to the whole piece?

No. An accidental applies only within the measure where it appears (and to that specific pitch). The key signature is what applies sharps or flats to the entire piece. The barline effectively resets accidentals.

### How is an accidental different from a key signature?

A key signature sits at the start of the staff and alters every instance of those letter names throughout the piece. An accidental sits next to one notehead and overrides the key signature temporarily, usually just for that measure.

### Where do you write an accidental, before or after the note?

Always to the left of (before) the notehead, on the same line or space as the note. This is explicitly stated in the AP CED, and writing it on the wrong side counts as a notation error on FRQs.

### Is C♯ the same note as D♭?

They sound identical (same key on the piano) but are spelled with different letter names and accidentals, making them enharmonic equivalents. AP questions can ask you to recognize or rewrite enharmonic spellings, so the distinction matters on paper even when it doesn't in sound.

## Related Study Guides

- [1.1 Pitch and Pitch Notation](/ap-music-theory/unit-1/pitch-pitch-notation/study-guide/kPffH0nOB4SulIxg9C8i)

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