diff --git a/mkdocs.yml b/mkdocs.yml
index c81a99bc26..bcb750c56f 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -18,6 +18,7 @@ nav:
           - Intracranial Electroencephalography: modality-specific-files/intracranial-electroencephalography.md
           - Physiological recordings: modality-specific-files/physiological-recordings.md
           - Behavioral experiments (with no neural recordings): modality-specific-files/behavioral-experiments.md
+          - Survey data (instrument-based phenotypic): modality-specific-files/survey.md
           - Genetic Descriptor: modality-specific-files/genetic-descriptor.md
           - Positron Emission Tomography: modality-specific-files/positron-emission-tomography.md
           - Microscopy: modality-specific-files/microscopy.md
diff --git a/src/modality-specific-files/survey.md b/src/modality-specific-files/survey.md
new file mode 100644
index 0000000000..d56bbfd457
--- /dev/null
+++ b/src/modality-specific-files/survey.md
@@ -0,0 +1,150 @@
+# Survey data (instrument-based phenotypic)
+
+Survey data files contain responses collected from standardized questionnaires or
+assessment instruments.
+They are organized in the same subject- and session-resolved directory hierarchy
+as other BIDS modalities, with one `.tsv` data file per instrument administration
+and a corresponding `.json` sidecar that documents the instrument and its items.
+
+This representation complements the aggregated `phenotype/` tables described in
+[Phenotypic and assessment data](../modality-agnostic-files/phenotypic-and-assessment-data.md).
+Aggregated phenotype tables MAY be generated from subject-resolved survey data
+and stored under `phenotype/`,
+but the subject-resolved structure is the primary canonical form.
+
+<!--
+This block generates a filename templates.
+The inputs for this macro can be found in the directory
+  src/schema/rules/files/raw
+and a guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filename_template("raw", datatypes=["survey"]) }}
+
+Survey files MUST be stored in a `survey` subdirectory of the subject (and
+optionally session) directory.
+The `task` entity identifies the instrument (for example, `task-pss` for the
+Perceived Stress Scale).
+The `run` entity MAY be used when the same instrument is administered more than
+once within a session.
+
+## Sidecar JSON (`*_survey.json`)
+
+Each survey `.tsv` file MUST be accompanied by a JSON sidecar.
+Following the [Inheritance Principle](../common-principles.md#the-inheritance-principle),
+the sidecar MAY be placed at any level of the hierarchy
+(for example, at the dataset root as `task-<label>_survey.json`)
+to apply to all survey files with matching entities,
+or alongside individual `.tsv` files with the same filename stem.
+The sidecar documents the instrument-level metadata and the individual items.
+
+### Instrument metadata
+
+The following top-level fields describe the survey instrument and its
+administration context.
+
+| Field                  | Requirement | Description                                                                                          |
+| ---------------------- | ----------- | ---------------------------------------------------------------------------------------------------- |
+| `TaskName`             | REQUIRED    | Short label identifying the instrument as used in this dataset (MUST match the `task` entity value). |
+| `OriginalName`         | REQUIRED    | Full canonical name of the instrument.                                                               |
+| `StimulusType`         | REQUIRED    | MUST be `"Questionnaire"`.                                                                           |
+| `FileFormat`           | REQUIRED    | MUST be `"tsv"`.                                                                                     |
+| `Language`             | REQUIRED    | Language code for the administered version (for example, `"en"`, `"de-AT"`).                         |
+| `Respondent`           | REQUIRED    | Who provided the responses (`"self"`, `"clinician"`, `"parent"`, or similar).                        |
+| `ShortName`            | OPTIONAL    | Common abbreviation of the instrument (for example, `"ESQ-3"`).                                      |
+| `Version`              | OPTIONAL    | Version or edition of the instrument.                                                                |
+| `Authors`              | OPTIONAL    | Array of instrument authors.                                                                         |
+| `DOI`                  | OPTIONAL    | DOI for the instrument or its primary validation paper.                                              |
+| `License`              | OPTIONAL    | License under which the instrument may be used.                                                      |
+| `Construct`            | OPTIONAL    | Psychological or clinical construct measured (for example, `"sleep quality"`).                       |
+| `Instructions`         | OPTIONAL    | Instructions given to the participant.                                                               |
+| `AdministrationMethod` | OPTIONAL    | How the instrument was administered (`"online"`, `"paper"`, `"interview"`, `"phone"`, or `"mixed"`). |
+| `SoftwarePlatform`     | OPTIONAL    | Software used to administer the instrument (for example, `"LimeSurvey"`, `"REDCap"`).                |
+
+### Item-level metadata
+
+Any top-level key in the sidecar that is not one of the instrument-level fields
+listed above is treated as a column-level variable definition (for example, `"Q01"`,
+`"item_1"`).
+
+| Field         | Requirement | Description                                                                                         |
+| ------------- | ----------- | --------------------------------------------------------------------------------------------------- |
+| `Description` | REQUIRED    | The exact text of the question or item.                                                             |
+| `Levels`      | OPTIONAL    | Mapping of response values to their labels (for example, `{"0": "Not at all", "4": "Very often"}`). |
+| `MinValue`    | OPTIONAL    | Minimum expected value.                                                                             |
+| `MaxValue`    | OPTIONAL    | Maximum expected value.                                                                             |
+| `DataType`    | OPTIONAL    | Expected data type of the column (`"string"`, `"integer"`, or `"float"`).                           |
+| `Units`       | OPTIONAL    | Units, if applicable.                                                                               |
+
+## Example dataset structure
+
+```text
+study/
+├── dataset_description.json
+├── participants.tsv
+├── task-sleep_survey.json
+├── sub-01/
+│   ├── ses-baseline/
+│   │   └── survey/
+│   │       └── sub-01_ses-baseline_task-sleep_run-01_survey.tsv
+│   └── ses-week04/
+│       └── survey/
+│           ├── sub-01_ses-week04_task-sleep_run-01_survey.tsv
+│           └── sub-01_ses-week04_task-sleep_run-02_survey.tsv
+└── phenotype/
+    └── sleep_summary.tsv
+```
+
+The root-level `task-sleep_survey.json` applies to all `task-sleep` survey files
+through the inheritance principle, avoiding duplication across sessions and runs.
+The `phenotype/` entry is an optional aggregated downstream view of the subject-resolved survey data.
+
+## Example `*_survey.tsv`
+
+```tsv
+participant_id	Q01	Q02	Q03
+sub-01	7	4	0
+```
+
+## Example `task-sleep_survey.json`
+
+```json
+{
+  "TaskName": "sleep",
+  "OriginalName": "Example Sleep Questionnaire",
+  "ShortName": "ESQ-3",
+  "StimulusType": "Questionnaire",
+  "FileFormat": "tsv",
+  "Language": "en",
+  "Respondent": "self",
+  "AdministrationMethod": "online",
+  "Q01": {
+    "Description": "How many hours did you sleep last night?",
+    "MinValue": 0,
+    "MaxValue": 24,
+    "DataType": "float",
+    "Units": "h"
+  },
+  "Q02": {
+    "Description": "How would you rate your overall sleep quality?",
+    "Levels": {
+      "1": "Very poor",
+      "2": "Poor",
+      "3": "Fair",
+      "4": "Good",
+      "5": "Very good"
+    },
+    "MinValue": 1,
+    "MaxValue": 5,
+    "DataType": "integer"
+  },
+  "Q03": {
+    "Description": "Did you wake up during the night?",
+    "Levels": {
+      "0": "No",
+      "1": "Yes"
+    },
+    "DataType": "integer"
+  }
+}
+```
diff --git a/src/schema/objects/datatypes.yaml b/src/schema/objects/datatypes.yaml
index b3fdc455e3..53200bf84e 100644
--- a/src/schema/objects/datatypes.yaml
+++ b/src/schema/objects/datatypes.yaml
@@ -76,3 +76,9 @@ nirs:
   value: nirs
   display_name: Near-Infrared Spectroscopy
   description: Near-Infrared Spectroscopy data organized around the SNIRF format
+survey:
+  value: survey
+  display_name: Survey data
+  description: |
+    Structured instrument-based phenotypic data (questionnaires and assessment
+    instruments) organized in a subject- and session-resolved directory hierarchy.
diff --git a/src/schema/objects/modalities.yaml b/src/schema/objects/modalities.yaml
index f363180534..fec377bb1d 100644
--- a/src/schema/objects/modalities.yaml
+++ b/src/schema/objects/modalities.yaml
@@ -42,3 +42,7 @@ nirs:
 mrs:
   display_name: Magnetic Resonance Spectroscopy
   description: Data acquired with MRS.
+survey:
+  display_name: Survey
+  description: |
+    Data collected with standardized questionnaires or assessment instruments.
diff --git a/src/schema/objects/suffixes.yaml b/src/schema/objects/suffixes.yaml
index 37cca59edf..138c597666 100644
--- a/src/schema/objects/suffixes.yaml
+++ b/src/schema/objects/suffixes.yaml
@@ -891,6 +891,14 @@ uCT:
   display_name: Micro-CT
   description: |
     Micro-CT imaging data
+survey:
+  value: survey
+  display_name: Survey
+  description: |
+    Instrument-based phenotypic survey data.
+    Responses collected from a structured questionnaire or assessment instrument,
+    organized as subject- and session-resolved tabular data with a corresponding
+    JSON sidecar.
 unloc:
   value: unloc
   display_name: Unlocalized spectroscopy
diff --git a/src/schema/rules/files/raw/survey.yaml b/src/schema/rules/files/raw/survey.yaml
new file mode 100644
index 0000000000..18fc8018be
--- /dev/null
+++ b/src/schema/rules/files/raw/survey.yaml
@@ -0,0 +1,11 @@
+---
+# Instrument-based phenotypic survey data
+survey:
+  $ref: meta.templates.raw.task
+  suffixes:
+    - survey
+  extensions:
+    - .tsv
+    - .json
+  datatypes:
+    - survey
diff --git a/src/schema/rules/modalities.yaml b/src/schema/rules/modalities.yaml
index 6aa492a8a0..658a735a87 100644
--- a/src/schema/rules/modalities.yaml
+++ b/src/schema/rules/modalities.yaml
@@ -37,3 +37,6 @@ nirs:
 mrs:
   datatypes:
     - mrs
+survey:
+  datatypes:
+    - survey