diff --git a/olmocr/train/dataloader.py b/olmocr/train/dataloader.py
index fab2229..401b7a7 100644
--- a/olmocr/train/dataloader.py
+++ b/olmocr/train/dataloader.py
@@ -1,12 +1,13 @@
 import base64
 import logging
 from abc import ABC, abstractmethod
+from concurrent.futures import ProcessPoolExecutor, as_completed
 from dataclasses import dataclass, fields
 from functools import reduce
 from io import BytesIO
 from os import PathLike
 from pathlib import Path
-from typing import Any, Callable, Dict, List, Optional, Type, TypeAlias
+from typing import Any, Callable, Dict, List, Optional, Type, TypeAlias, Tuple
 
 import numpy as np
 import yaml
@@ -26,6 +27,47 @@ Sample: TypeAlias = Dict[str, Any]
 logger = logging.getLogger(__name__)
 
 
+def validate_pdf_pair(md_path: Path) -> Tuple[Optional[Dict[str, Path]], Optional[Tuple[Path, str]]]:
+    """Validate a single markdown-PDF pair.
+    
+    Args:
+        md_path: Path to the markdown file
+        
+    Returns:
+        Tuple of (valid_sample, invalid_pdf_info)
+        - valid_sample: Dict with markdown_path and pdf_path if valid, None otherwise
+        - invalid_pdf_info: Tuple of (pdf_path, reason) if invalid, None otherwise
+    """
+    # Look for PDF with same stem (filename without extension)
+    pdf_path = md_path.with_suffix(".pdf")
+    
+    if pdf_path.exists() or pdf_path.is_symlink():
+        # Resolve symlink if it is one
+        if pdf_path.is_symlink():
+            pdf_path = pdf_path.resolve()
+        
+        # Verify the resolved path exists
+        if pdf_path.exists():
+            # Validate PDF - check it loads and has exactly one page and that you can get document-anchoring from it
+            try:
+                reader = PdfReader(str(pdf_path))
+                num_pages = len(reader.pages)
+                
+                if num_pages != 1:
+                    return None, (pdf_path, f"Expected 1 page, found {num_pages}")
+                
+                # Test that document anchoring works
+                from olmocr.prompts.anchor import get_anchor_text
+                get_anchor_text(pdf_path, page=1, pdf_engine="pdfreport", target_length=100)
+                
+                return {"markdown_path": md_path, "pdf_path": pdf_path}, None
+                
+            except Exception as e:
+                return None, (pdf_path, f"Failed to load: {str(e)}")
+    
+    return None, None
+
+
 @dataclass(frozen=True, slots=True)
 class PipelineStep(ABC):
     """Abstract base class for pipeline steps."""
@@ -55,39 +97,35 @@ class BaseMarkdownPDFDataset(Dataset):
         logger.info(f"Scanning for markdown files in {self.root_dir}...")
         md_files = list(self.root_dir.rglob("*.md"))
 
-        # Verify each markdown file has a corresponding PDF
+        # Verify each markdown file has a corresponding PDF using ProcessPoolExecutor
         valid_count = 0
         invalid_pdfs = []
 
-        logger.info(f"Validating {len(md_files)} markdown-PDF pairs...")
-        for md_path in tqdm(md_files, desc="Validating PDFs"):
-            # Look for PDF with same stem (filename without extension)
-            pdf_path = md_path.with_suffix(".pdf")
-
-            if pdf_path.exists() or pdf_path.is_symlink():
-                # Resolve symlink if it is one
-                if pdf_path.is_symlink():
-                    pdf_path = pdf_path.resolve()
-
-                # Verify the resolved path exists
-                if pdf_path.exists():
-                    # Validate PDF - check it loads and has exactly one page and that you can get document-anchoring from it
+        logger.info(f"Validating {len(md_files)} markdown-PDF pairs using ProcessPoolExecutor...")
+        
+        # Use ProcessPoolExecutor for parallel validation
+        with ProcessPoolExecutor(max_workers=8) as executor:
+            # Submit all validation tasks
+            future_to_md = {executor.submit(validate_pdf_pair, md_path): md_path for md_path in md_files}
+            
+            # Process results as they complete
+            with tqdm(total=len(md_files), desc="Validating PDFs") as pbar:
+                for future in as_completed(future_to_md):
+                    md_path = future_to_md[future]
                     try:
-                        reader = PdfReader(str(pdf_path))
-                        num_pages = len(reader.pages)
-
-                        if num_pages != 1:
-                            invalid_pdfs.append((pdf_path, f"Expected 1 page, found {num_pages}"))
-                            continue
-
-                        # Test that document anchoring works
-                        get_anchor_text(pdf_path, page=1, pdf_engine="pdfreport", target_length=100)
-
-                        self.samples.append({"markdown_path": md_path, "pdf_path": pdf_path})
-                        valid_count += 1
-
+                        valid_sample, invalid_pdf_info = future.result()
+                        
+                        if valid_sample:
+                            self.samples.append(valid_sample)
+                            valid_count += 1
+                        elif invalid_pdf_info:
+                            invalid_pdfs.append(invalid_pdf_info)
+                            
                     except Exception as e:
-                        invalid_pdfs.append((pdf_path, f"Failed to load: {str(e)}"))
+                        logger.error(f"Error processing {md_path}: {str(e)}")
+                        invalid_pdfs.append((md_path.with_suffix(".pdf"), f"Processing error: {str(e)}"))
+                    
+                    pbar.update(1)
 
         logger.info(f"Found {valid_count} valid markdown-PDF pairs")