diff --git a/src/reviewer/cli.py b/src/reviewer/cli.py
index c5828d7..5399490 100644
--- a/src/reviewer/cli.py
+++ b/src/reviewer/cli.py
@@ -194,6 +194,7 @@ def _build_paper_json(
             "explanation": c.explanation,
             "comment_type": c.comment_type,
             "paragraph_index": c.paragraph_index,
+            "severity": c.severity,
         })
 
     model_short = _model_short_name(result.model) if result.model else ""
diff --git a/src/reviewer/models.py b/src/reviewer/models.py
index 671bbc0..b00e9bb 100644
--- a/src/reviewer/models.py
+++ b/src/reviewer/models.py
@@ -2,6 +2,8 @@
 
 from dataclasses import dataclass, field
 
+SEVERITY_VALUES = ("minor", "moderate", "major")
+
 
 @dataclass
 class Comment:
@@ -11,6 +13,7 @@ class Comment:
     explanation: str    # reviewer's explanation
     comment_type: str   # "technical" or "logical"
     paragraph_index: int | None = None  # 0-based index in split paragraphs
+    severity: str | None = None         # one of SEVERITY_VALUES, or None when unknown
 
     def to_dict(self) -> dict:
         d = {
@@ -21,6 +24,8 @@ def to_dict(self) -> dict:
         }
         if self.paragraph_index is not None:
             d["paragraph_index"] = self.paragraph_index
+        if self.severity:
+            d["severity"] = self.severity
         return d
 
 
diff --git a/src/reviewer/prompts.py b/src/reviewer/prompts.py
index 6ca28f3..34b7968 100644
--- a/src/reviewer/prompts.py
+++ b/src/reviewer/prompts.py
@@ -41,12 +41,19 @@
 DO_NOT_FLAG_CHUNKED = DO_NOT_FLAG_BASE.rstrip() + """
 - Incomplete text at passage boundaries"""
 
+SEVERITY_RUBRIC = """\
+For each issue, assign a "severity" tier:
+- "major": undermines a key claim, methodology, or comparison; affects conclusions
+- "moderate": real error or gap, but localized and fixable
+- "minor": framing concern, mild overclaim, or ambiguity resolvable from context"""
+
 JSON_ARRAY_OUTPUT = """\
 Return ONLY a JSON array (can be []). Each item:
 - "title": concise title of the issue
 - "quote": the exact verbatim text (preserving LaTeX)
 - "explanation": deep reasoning — what you initially thought, whether context resolves it, and what specifically remains problematic
 - "type": "technical" or "logical"
+- "severity": "minor", "moderate", or "major"
 """
 
 # ── Deep-check prompt (used by local and progressive methods) ───────────────
@@ -73,6 +80,8 @@
 
 {DO_NOT_FLAG_CHUNKED}
 
+{SEVERITY_RUBRIC}
+
 {JSON_ARRAY_OUTPUT}"""
 
 
@@ -98,6 +107,8 @@
 
 {DO_NOT_FLAG_BASE}
 
+{SEVERITY_RUBRIC}
+
 Return a JSON object with this structure:
 {{{{
   "overall_feedback": "one paragraph high-level assessment of the paper's quality and main issues",
@@ -106,7 +117,8 @@
       "title": "concise title of the issue",
       "quote": "exact verbatim text from the paper (preserving LaTeX)",
       "explanation": "precise explanation of what is wrong and why",
-      "type": "technical" or "logical"
+      "type": "technical" or "logical",
+      "severity": "minor" or "moderate" or "major"
     }}}}
   ]
 }}}}
@@ -133,6 +145,8 @@
 
 {DO_NOT_FLAG_CHUNKED}
 
+{SEVERITY_RUBRIC}
+
 Return a JSON object with this structure:
 {{{{
   "overall_feedback": "brief assessment of this section",
@@ -141,7 +155,8 @@
       "title": "concise title of the issue",
       "quote": "exact verbatim text from the paper (preserving LaTeX)",
       "explanation": "precise explanation of what is wrong and why",
-      "type": "technical" or "logical"
+      "type": "technical" or "logical",
+      "severity": "minor" or "moderate" or "major"
     }}}}
   ]
 }}}}
diff --git a/src/reviewer/utils.py b/src/reviewer/utils.py
index ec62cce..347e926 100644
--- a/src/reviewer/utils.py
+++ b/src/reviewer/utils.py
@@ -6,7 +6,7 @@
 
 import tiktoken
 
-from .models import Comment
+from .models import Comment, SEVERITY_VALUES
 
 
 def _get_encoding():
@@ -205,12 +205,18 @@ def parse_comments_from_list(items: list[dict]) -> list[Comment]:
         paragraph_index = item.get("paragraph_index", None)
         if paragraph_index is not None:
             paragraph_index = int(paragraph_index)
+        severity = item.get("severity")
+        if isinstance(severity, str):
+            severity = severity.strip().lower()
+        if severity not in SEVERITY_VALUES:
+            severity = "moderate"
         comments.append(Comment(
             title=title,
             quote=quote,
             explanation=explanation,
             comment_type=comment_type,
             paragraph_index=paragraph_index,
+            severity=severity,
         ))
     return comments