diff --git a/CHANGELOG.md b/CHANGELOG.md
index e4cf496..563fc9c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
-Nothing
+### Fixed
+- Grouping of text lines outside of parent container bounding box ([#386](https://github.com/pdfminer/pdfminer.six/pull/386))
 
 ## [20200124] - 2020-01-24
 
diff --git a/pdfminer/layout.py b/pdfminer/layout.py
index 8c22622..312cdec 100644
--- a/pdfminer/layout.py
+++ b/pdfminer/layout.py
@@ -597,16 +597,14 @@ class LTLayoutContainer(LTContainer):
         yield line
         return
 
-    # group_textlines: group neighboring lines to textboxes.
     def group_textlines(self, laparams, lines):
+        """Group neighboring lines to textboxes"""
         plane = Plane(self.bbox)
         plane.extend(lines)
         boxes = {}
         for line in lines:
             neighbors = line.find_neighbors(plane, laparams.line_margin)
-            if line not in neighbors:
-                continue
-            members = []
+            members = [line]
             for obj1 in neighbors:
                 members.append(obj1)
                 if obj1 in boxes:
diff --git a/tests/test_layout.py b/tests/test_layout.py
new file mode 100644
index 0000000..a6788a3
--- /dev/null
+++ b/tests/test_layout.py
@@ -0,0 +1,23 @@
+import unittest
+
+from pdfminer.layout import LTLayoutContainer, LAParams, LTTextLineHorizontal
+
+
+class TestGroupTextLines(unittest.TestCase):
+    def test_parent_with_wrong_bbox_returns_non_empty_neighbour_list(self):
+        """
+        LTLayoutContainer.group_textlines() should return all the lines in a
+        separate LTTextBoxes if they do not overlap. Even when the bounding box
+        of the parent container does not contain all the lines.
+        """
+        laparams = LAParams()
+        layout = LTLayoutContainer((0, 0, 50, 50))
+        line1 = LTTextLineHorizontal(laparams.word_margin)
+        line1.set_bbox((0, 0, 50, 5))
+        line2 = LTTextLineHorizontal(laparams.word_margin)
+        line2.set_bbox((0, 50, 50, 55))
+        lines = [line1, line2]
+
+        textboxes = list(layout.group_textlines(laparams, lines))
+
+        self.assertEqual(len(textboxes), 2)
diff --git a/tools/pdf2txt.py b/tools/pdf2txt.py
index bc22329..2332135 100755
--- a/tools/pdf2txt.py
+++ b/tools/pdf2txt.py
@@ -122,7 +122,7 @@ def maketheparser():
              "should be within the range of -1.0 (only horizontal position "
              "matters) to +1.0 (only vertical position matters).")
     la_params.add_argument(
-        "--all-texts", "-A", default=True, action="store_true",
+        "--all-texts", "-A", default=False, action="store_true",
         help="If layout analysis should be performed on text in figures.")
 
     output_params = parser.add_argument_group(