diff --git a/.env-example b/.env-example
index e6aa060..16a6d9d 100644
--- a/.env-example
+++ b/.env-example
@@ -4,3 +4,4 @@ WEBLOGIN_SECRET=your-weblogin-secret
 WEBLOGIN_ID=your-weblogin-id'
 WEBLOGIN_ON=true
 CATALOG_SOLR=http://url-to-solr/solr/biblio
+MAX_THREADS=5
diff --git a/Gemfile.lock b/Gemfile.lock
index 5426f6a..4c6b55c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -17,6 +17,8 @@ GEM
     byebug (11.1.3)
     coderay (1.1.3)
     concurrent-ruby (1.1.10)
+    concurrent-ruby-ext (1.1.10)
+      concurrent-ruby (= 1.1.10)
     crack (0.4.5)
       rexml
     diff-lcs (1.5.0)
@@ -167,6 +169,8 @@ PLATFORMS
 
 DEPENDENCIES
   byebug
+  concurrent-ruby
+  concurrent-ruby-ext
   faraday
   faraday-retry
   net-smtp
diff --git a/lib/report_generator.rb b/lib/report_generator.rb
index 7a36f5d..e3a27ba 100644
--- a/lib/report_generator.rb
+++ b/lib/report_generator.rb
@@ -2,22 +2,31 @@ class ReportGenerator
   def initialize(barcodes: [])
     @barcodes = barcodes
     @umich_catalog_items = UmichCatalogItems.for(barcodes: @barcodes)
+    Logger.new($stdout).info("fetched umich catalog items")
   end
 
   def run
     queue = Queue.new
     queue.push(header_row)
 
-    @barcodes.each do |barcode|
-      umich_item = @umich_catalog_items.item_for_barcode(barcode)
-      next if umich_item.nil?
-      worldcat_summary = WorldCatSummary.for(umich_item.oclc || [])
+    barcode_queue = @barcodes.inject(Queue.new, :push)
 
-      queue.push(
-        format_line(umich_item: umich_item, worldcat_summary: worldcat_summary)
-      )
+    threads = Array.new(ENV.fetch(MAX_THREADS)) do
+      Thread.new do
+        until barcode_queue.empty?
+          barcode = barcode_queue.shift
+          umich_item = @umich_catalog_items.item_for_barcode(barcode)
+          next if umich_item.nil?
+          worldcat_summary = WorldCatSummary.for(umich_item.oclc || [])
+
+          queue.push(
+            format_line(umich_item: umich_item, worldcat_summary: worldcat_summary)
+          )
+        end
+      end
     end
 
+    threads.each(&:join)
     print(queue)
   end