diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 253813a5c..7ea007247 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -288,7 +288,7 @@ Metrics/BlockNesting:
 # Offense count: 3
 # Configuration parameters: CountComments.
 Metrics/ClassLength:
-  Max: 149
+  Max: 170
 
 # Offense count: 12
 Metrics/CyclomaticComplexity:
@@ -302,7 +302,7 @@ Metrics/MethodLength:
 # Offense count: 1
 # Configuration parameters: CountComments.
 Metrics/ModuleLength:
-  Max: 125
+  Max: 140
   Exclude:
     - 'lib/bugsnag/helpers.rb'
 
diff --git a/lib/bugsnag.rb b/lib/bugsnag.rb
index e217ec161..42cc8d924 100644
--- a/lib/bugsnag.rb
+++ b/lib/bugsnag.rb
@@ -29,6 +29,10 @@
 require "bugsnag/middleware/classify_error"
 require "bugsnag/middleware/delayed_job"
 
+require "bugsnag/breadcrumbs/validator"
+require "bugsnag/breadcrumbs/breadcrumb"
+require "bugsnag/breadcrumbs/breadcrumbs"
+
 module Bugsnag
   LOCK = Mutex.new
   INTEGRATIONS = [:resque, :sidekiq, :mailman, :delayed_job, :shoryuken, :que]
@@ -189,6 +193,36 @@ def load_integration(integration)
       end
     end
 
+    ##
+    # Leave a breadcrumb to be attached to subsequent reports
+    #
+    # @param name [String] the main breadcrumb name/message
+    # @param meta_data [Hash] String, Numeric, or Boolean meta data to attach
+    # @param type [String] the breadcrumb type, from Bugsnag::Breadcrumbs::VALID_BREADCRUMB_TYPES
+    # @param auto [Symbol] set to :auto if the breadcrumb is automatically created
+    def leave_breadcrumb(name, meta_data={}, type=Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE, auto=:manual)
+      breadcrumb = Bugsnag::Breadcrumbs::Breadcrumb.new(name, type, meta_data, auto)
+      validator = Bugsnag::Breadcrumbs::Validator.new(configuration)
+
+      # Initial validation
+      validator.validate(breadcrumb)
+
+      # Skip if it's already invalid
+      unless breadcrumb.ignore?
+        # Run callbacks
+        configuration.before_breadcrumb_callbacks.each do |c|
+          (c.arity > 0 ? c.call(breadcrumb) : c.call)
+          break if breadcrumb.ignore?
+        end
+
+        # Validate again incase of callback alteration
+        validator.validate(breadcrumb)
+
+        # Add to breadcrumbs buffer if still valid
+        configuration.breadcrumbs << breadcrumb unless breadcrumb.ignore?
+      end
+    end
+
     private
 
     def deliver_notification?(exception, auto_notify)
diff --git a/lib/bugsnag/configuration.rb b/lib/bugsnag/configuration.rb
index 56a52db84..ab1716bbc 100644
--- a/lib/bugsnag/configuration.rb
+++ b/lib/bugsnag/configuration.rb
@@ -8,6 +8,7 @@
 require "bugsnag/middleware/suggestion_data"
 require "bugsnag/middleware/classify_error"
 require "bugsnag/middleware/session_data"
+require "bugsnag/middleware/breadcrumbs"
 require "bugsnag/utility/circular_buffer"
 require "bugsnag/breadcrumbs/breadcrumbs"
 
@@ -118,6 +119,7 @@ def initialize
       self.internal_middleware.use Bugsnag::Middleware::SuggestionData
       self.internal_middleware.use Bugsnag::Middleware::ClassifyError
       self.internal_middleware.use Bugsnag::Middleware::SessionData
+      self.internal_middleware.use Bugsnag::Middleware::Breadcrumbs
 
       self.middleware = Bugsnag::MiddlewareStack.new
       self.middleware.use Bugsnag::Middleware::Callbacks
diff --git a/lib/bugsnag/middleware/breadcrumbs.rb b/lib/bugsnag/middleware/breadcrumbs.rb
new file mode 100644
index 000000000..3b5ffab97
--- /dev/null
+++ b/lib/bugsnag/middleware/breadcrumbs.rb
@@ -0,0 +1,21 @@
+module Bugsnag::Middleware
+  ##
+  # Adds breadcrumbs to the report
+  class Breadcrumbs
+    ##
+    # @param next_callable [#call] the next callable middleware
+    def initialize(next_callable)
+      @next = next_callable
+    end
+
+    ##
+    # Execute this middleware
+    #
+    # @param report [Bugsnag::Report] the report being iterated over
+    def call(report)
+      breadcrumbs = report.configuration.breadcrumbs.to_a
+      report.breadcrumbs = breadcrumbs unless breadcrumbs.empty?
+      @next.call(report)
+    end
+  end
+end
diff --git a/lib/bugsnag/report.rb b/lib/bugsnag/report.rb
index 537d03902..9d5e78a66 100644
--- a/lib/bugsnag/report.rb
+++ b/lib/bugsnag/report.rb
@@ -23,13 +23,16 @@ class Report
     attr_accessor :api_key
     attr_accessor :app_type
     attr_accessor :app_version
+    attr_accessor :breadcrumbs
     attr_accessor :configuration
     attr_accessor :context
     attr_accessor :delivery_method
     attr_accessor :exceptions
     attr_accessor :hostname
     attr_accessor :grouping_hash
+    attr_accessor :message
     attr_accessor :meta_data
+    attr_accessor :name
     attr_accessor :raw_exceptions
     attr_accessor :release_stage
     attr_accessor :session
@@ -51,9 +54,14 @@ def initialize(exception, passed_configuration, auto_notify=false)
       self.api_key = configuration.api_key
       self.app_type = configuration.app_type
       self.app_version = configuration.app_version
+      self.breadcrumbs = []
       self.delivery_method = configuration.delivery_method
       self.hostname = configuration.hostname
+      self.message = defined?(exception.message) ? exception.message : exception.to_s
       self.meta_data = {}
+
+      # Notified strings display as RuntimeErrors in the dashboard
+      self.name = exception.is_a?(Exception) ? exception.class.to_s : RuntimeError.to_s
       self.release_stage = configuration.release_stage
       self.severity = auto_notify ? "error" : "warning"
       self.severity_reason = auto_notify ? {:type => UNHANDLED_EXCEPTION} : {:type => HANDLED_EXCEPTION}
@@ -110,7 +118,14 @@ def as_json
       payload_event = Bugsnag::Cleaner.clean_object_encoding(payload_event)
 
       # filter out sensitive values in (and cleanup encodings) metaData
-      payload_event[:metaData] = Bugsnag::Cleaner.new(configuration.meta_data_filters).clean_object(meta_data)
+      filter_cleaner = Bugsnag::Cleaner.new(configuration.meta_data_filters)
+      payload_event[:metaData] = filter_cleaner.clean_object(meta_data)
+      payload_event[:breadcrumbs] = breadcrumbs.map do |breadcrumb|
+        breadcrumb_hash = breadcrumb.to_h
+        breadcrumb_hash[:metaData] = filter_cleaner.clean_object(breadcrumb_hash[:metaData])
+        breadcrumb_hash
+      end
+
       payload_event.reject! {|k,v| v.nil? }
 
       # return the payload hash
@@ -153,6 +168,18 @@ def ignore!
       @should_ignore = true
     end
 
+    ##
+    # Generates a summary to be attached as a breadcrumb
+    #
+    # @return [Hash] a Hash containing the report's name, message, and severity
+    def summary
+      {
+        :name => name,
+        :message => message,
+        :severity => severity
+      }
+    end
+
     private
 
     def generate_exception_list
diff --git a/spec/bugsnag_spec.rb b/spec/bugsnag_spec.rb
index 8e8e8a5b5..c83ce288d 100644
--- a/spec/bugsnag_spec.rb
+++ b/spec/bugsnag_spec.rb
@@ -133,4 +133,153 @@ module Kernel
       Kernel.send(:remove_const, :REQUIRED)
     end
   end
+
+  describe "#leave_breadcrumb" do
+
+    let(:breadcrumbs) { Bugsnag.configuration.breadcrumbs }
+    let(:timestamp_regex) { /^\d{4}\-\d{2}\-\d{2}T\d{2}:\d{2}:[\d\.]+Z$/ }
+
+    it "requires only a name argument" do
+      Bugsnag.leave_breadcrumb("TestName")
+      expect(breadcrumbs.to_a.size).to eq(1)
+      expect(breadcrumbs.first.to_h).to match({
+        :name => "TestName",
+        :type => Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE,
+        :metaData => {},
+        :timestamp => match(timestamp_regex)
+      })
+    end
+
+    it "accepts meta_data" do
+      Bugsnag.leave_breadcrumb("TestName", { :a => 1, :b => "2" })
+      expect(breadcrumbs.to_a.size).to eq(1)
+      expect(breadcrumbs.first.to_h).to match({
+        :name => "TestName",
+        :type => Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE,
+        :metaData => { :a => 1, :b => "2" },
+        :timestamp => match(timestamp_regex)
+      })
+    end
+
+    it "allows different message types" do
+      Bugsnag.leave_breadcrumb("TestName", {}, Bugsnag::Breadcrumbs::ERROR_BREADCRUMB_TYPE)
+      expect(breadcrumbs.to_a.size).to eq(1)
+      expect(breadcrumbs.first.to_h).to match({
+        :name => "TestName",
+        :type => Bugsnag::Breadcrumbs::ERROR_BREADCRUMB_TYPE,
+        :metaData => {},
+        :timestamp => match(timestamp_regex)
+      })
+    end
+
+    it "validates before leaving" do
+      Bugsnag.leave_breadcrumb(
+        "123123123123123123123123123123456456456456456456456456456456",
+        {
+          :a => 1,
+          :b => [1, 2, 3, 4],
+          :c => {
+            :test => true,
+            :test2 => false
+          }
+        },
+        "Not a real type"
+      )
+      expect(breadcrumbs.to_a.size).to eq(1)
+      expect(breadcrumbs.first.to_h).to match({
+        :name => "123123123123123123123123123123",
+        :type => Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE,
+        :metaData => {
+          :a => 1
+        },
+        :timestamp => match(timestamp_regex)
+      })
+    end
+
+    it "runs callbacks before leaving" do
+      Bugsnag.configuration.before_breadcrumb_callbacks << Proc.new { |breadcrumb|
+        breadcrumb.meta_data = {
+          :callback => true
+        }
+      }
+      Bugsnag.leave_breadcrumb("TestName")
+      expect(breadcrumbs.to_a.size).to eq(1)
+      expect(breadcrumbs.first.to_h).to match({
+        :name => "TestName",
+        :type => Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE,
+        :metaData => {
+          :callback => true
+        },
+        :timestamp => match(timestamp_regex)
+      })
+    end
+
+    it "validates after callbacks" do
+      Bugsnag.configuration.before_breadcrumb_callbacks << Proc.new { |breadcrumb|
+        breadcrumb.meta_data = {
+          :int => 1,
+          :array => [1, 2, 3],
+          :hash => {
+            :a => 1,
+            :b => 2
+          }
+        }
+        breadcrumb.type = "Not a real type"
+        breadcrumb.name = "123123123123123123123123123123456456456456456"
+      }
+      Bugsnag.leave_breadcrumb("TestName")
+      expect(breadcrumbs.to_a.size).to eq(1)
+      expect(breadcrumbs.first.to_h).to match({
+        :name => "123123123123123123123123123123",
+        :type => Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE,
+        :metaData => {
+          :int => 1
+        },
+        :timestamp => match(timestamp_regex)
+      })
+    end
+
+    it "doesn't add when ignored by the validator" do
+      Bugsnag.configuration.automatic_breadcrumb_types = []
+      Bugsnag.leave_breadcrumb("TestName", {}, Bugsnag::Breadcrumbs::ERROR_BREADCRUMB_TYPE, :auto)
+      expect(breadcrumbs.to_a.size).to eq(0)
+    end
+
+    it "doesn't add if ignored in a callback" do
+      Bugsnag.configuration.before_breadcrumb_callbacks << Proc.new { |breadcrumb|
+        breadcrumb.ignore!
+      }
+      Bugsnag.leave_breadcrumb("TestName")
+      expect(breadcrumbs.to_a.size).to eq(0)
+    end
+
+    it "doesn't add when ignored after the callbacks" do
+      Bugsnag.configuration.automatic_breadcrumb_types = [
+        Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE
+      ]
+      Bugsnag.configuration.before_breadcrumb_callbacks << Proc.new { |breadcrumb|
+        breadcrumb.type = Bugsnag::Breadcrumbs::ERROR_BREADCRUMB_TYPE
+      }
+      Bugsnag.leave_breadcrumb("TestName", {}, Bugsnag::Breadcrumbs::MANUAL_BREADCRUMB_TYPE, :auto)
+      expect(breadcrumbs.to_a.size).to eq(0)
+    end
+
+    it "doesn't call callbacks if ignored early" do
+      Bugsnag.configuration.automatic_breadcrumb_types = []
+      Bugsnag.configuration.before_breadcrumb_callbacks << Proc.new { |breadcrumb|
+        fail "This shouldn't be called"
+      }
+      Bugsnag.leave_breadcrumb("TestName", {}, Bugsnag::Breadcrumbs::ERROR_BREADCRUMB_TYPE, :auto)
+    end
+
+    it "doesn't continue to call callbacks if ignored in them" do
+      Bugsnag.configuration.before_breadcrumb_callbacks << Proc.new { |breadcrumb|
+        breadcrumb.ignore!
+      }
+      Bugsnag.configuration.before_breadcrumb_callbacks << Proc.new { |breadcrumb|
+        fail "This shouldn't be called"
+      }
+      Bugsnag.leave_breadcrumb("TestName")
+    end
+  end
 end
diff --git a/spec/report_spec.rb b/spec/report_spec.rb
index 32bcd4b39..cbb80afee 100644
--- a/spec/report_spec.rb
+++ b/spec/report_spec.rb
@@ -1092,6 +1092,104 @@ def gloops
     }
   end
 
+  describe "breadcrumbs" do
+    let(:timestamp_regex) { /^\d{4}\-\d{2}\-\d{2}T\d{2}:\d{2}:[\d\.]+Z$/ }
+
+    it "includes left breadcrumbs" do
+      Bugsnag.leave_breadcrumb("Test breadcrumb")
+      notify_test_exception
+      expect(Bugsnag).to have_sent_notification{ |payload, headers|
+        event = get_event_from_payload(payload)
+        expect(event["breadcrumbs"].size).to eq(1)
+        expect(event["breadcrumbs"].first).to match({
+          "name" => "Test breadcrumb",
+          "type" => "manual",
+          "metaData" => {},
+          "timestamp" => match(timestamp_regex)
+        })
+      }
+    end
+
+    it "filters left breadcrumbs" do
+      Bugsnag.leave_breadcrumb("Test breadcrumb", {
+        :forbidden_key => false,
+        :allowed_key => true
+      })
+      Bugsnag.configuration.meta_data_filters << "forbidden"
+      notify_test_exception
+      expect(Bugsnag).to have_sent_notification{ |payload, headers|
+        event = get_event_from_payload(payload)
+        expect(event["breadcrumbs"].size).to eq(1)
+        expect(event["breadcrumbs"].first).to match({
+          "name" => "Test breadcrumb",
+          "type" => "manual",
+          "metaData" => {
+            "forbidden_key" => "[FILTERED]",
+            "allowed_key" => true
+          },
+          "timestamp" => match(timestamp_regex)
+        })
+      }
+    end
+
+    it "defaults to an empty array" do
+      notify_test_exception
+      expect(Bugsnag).to have_sent_notification{ |payload, headers|
+        event = get_event_from_payload(payload)
+        expect(event["breadcrumbs"].size).to eq(0)
+      }
+    end
+
+    it "allows breadcrumbs to be editted in callbacks" do
+      Bugsnag.leave_breadcrumb("Test breadcrumb")
+      Bugsnag.before_notify_callbacks << Proc.new { |report|
+        breadcrumb = report.breadcrumbs.first
+        breadcrumb.meta_data = {:a => 1, :b => 2}
+      }
+      notify_test_exception
+      expect(Bugsnag).to have_sent_notification{ |payload, headers|
+        event = get_event_from_payload(payload)
+        expect(event["breadcrumbs"].size).to eq(1)
+        expect(event["breadcrumbs"].first).to match({
+          "name" => "Test breadcrumb",
+          "type" => "manual",
+          "metaData" => {"a" => 1, "b" => 2},
+          "timestamp" => match(timestamp_regex)
+        })
+      }
+    end
+  end
+
+  describe "#summary" do
+    it "provides a hash of the name, message, and severity" do
+      begin
+        1/0
+      rescue ZeroDivisionError => e
+        report = Bugsnag::Report.new(e, Bugsnag.configuration)
+        expect(report.name).to eq("ZeroDivisionError")
+        expect(report.message).to eq("divided by 0")
+
+        expect(report.summary).to match({
+          :name => "ZeroDivisionError",
+          :message => "divided by 0",
+          :severity => "warning"
+        })
+      end
+    end
+
+    it "handles strings" do
+      report = Bugsnag::Report.new("test string", Bugsnag.configuration)
+      expect(report.name).to eq("RuntimeError")
+      expect(report.message).to eq("test string")
+
+      expect(report.summary).to match({
+        :name => "RuntimeError",
+        :message => "test string",
+        :severity => "warning"
+      })
+    end
+  end
+
   if defined?(JRUBY_VERSION)
 
     it "should work with java.lang.Throwables" do