diff --git a/colosseum/constants.py b/colosseum/constants.py
index e5a45e5fc..5edd7b138 100644
--- a/colosseum/constants.py
+++ b/colosseum/constants.py
@@ -254,6 +254,12 @@ def value(self, context):
 # 10.8 Leading and half-leading
 ######################################################################
 # line_height
+LINE_HEIGHT_CHOICES = Choices(
+    NORMAL,
+    validators=[is_number, is_length, is_percentage],
+    explicit_defaulting_constants=[INHERIT],
+)
+
 # vertical_align
 
 ######################################################################
diff --git a/colosseum/declaration.py b/colosseum/declaration.py
index 40320cbb8..31a19beee 100644
--- a/colosseum/declaration.py
+++ b/colosseum/declaration.py
@@ -1,30 +1,31 @@
-from . import engine as css_engine
-from . import parser
+from . import engine as css_engine, parser
 from .constants import (  # noqa
     ALIGN_CONTENT_CHOICES, ALIGN_ITEMS_CHOICES, ALIGN_SELF_CHOICES, AUTO,
     BACKGROUND_COLOR_CHOICES, BORDER_COLLAPSE_CHOICES, BORDER_COLOR_CHOICES,
     BORDER_SPACING_CHOICES, BORDER_STYLE_CHOICES, BORDER_WIDTH_CHOICES,
     BOX_OFFSET_CHOICES, CAPTION_SIDE_CHOICES, CLEAR_CHOICES, CLIP_CHOICES,
-    COLOR_CHOICES, DIRECTION_CHOICES, DISPLAY_CHOICES, EMPTY_CELLS_CHOICES,
-    FLEX_BASIS_CHOICES, FLEX_DIRECTION_CHOICES, FLEX_GROW_CHOICES,
-    FLEX_SHRINK_CHOICES, FLEX_START, FLEX_WRAP_CHOICES, FLOAT_CHOICES,
-    GRID_AUTO_CHOICES, GRID_AUTO_FLOW_CHOICES, GRID_GAP_CHOICES,
+    COLOR_CHOICES, CURSOR_CHOICES, DIRECTION_CHOICES, DISPLAY_CHOICES,
+    EMPTY_CELLS_CHOICES, FLEX_BASIS_CHOICES, FLEX_DIRECTION_CHOICES,
+    FLEX_GROW_CHOICES, FLEX_SHRINK_CHOICES, FLEX_START, FLEX_WRAP_CHOICES,
+    FLOAT_CHOICES, GRID_AUTO_CHOICES, GRID_AUTO_FLOW_CHOICES, GRID_GAP_CHOICES,
     GRID_PLACEMENT_CHOICES, GRID_TEMPLATE_AREA_CHOICES, GRID_TEMPLATE_CHOICES,
     INITIAL, INLINE, INVERT, JUSTIFY_CONTENT_CHOICES, LETTER_SPACING_CHOICES,
-    LTR, MARGIN_CHOICES, MAX_SIZE_CHOICES, MEDIUM, MIN_SIZE_CHOICES, NORMAL,
-    NOWRAP, ORDER_CHOICES, ORPHANS_CHOICES, OUTLINE_COLOR_CHOICES,
-    OUTLINE_STYLE_CHOICES, OUTLINE_WIDTH_CHOICES, OVERFLOW_CHOICES,
-    PADDING_CHOICES, PAGE_BREAK_AFTER_CHOICES, PAGE_BREAK_BEFORE_CHOICES,
-    PAGE_BREAK_INSIDE_CHOICES, POSITION_CHOICES, QUOTES_CHOICES, ROW,
-    SEPARATE, SHOW, SIZE_CHOICES, STATIC, STRETCH, TABLE_LAYOUT_CHOICES,
-    TEXT_ALIGN_CHOICES, TEXT_DECORATION_CHOICES, TEXT_INDENT_CHOICES,
-    TEXT_TRANSFORM_CHOICES, TOP, TRANSPARENT, UNICODE_BIDI_CHOICES,
-    VISIBILITY_CHOICES, VISIBLE, WHITE_SPACE_CHOICES, WIDOWS_CHOICES,
-    WORD_SPACING_CHOICES, Z_INDEX_CHOICES, OtherProperty,
-    TextAlignInitialValue, default, CURSOR_CHOICES,
+    LINE_HEIGHT_CHOICES, LTR, MARGIN_CHOICES, MAX_SIZE_CHOICES, MEDIUM,
+    MIN_SIZE_CHOICES, NORMAL, NOWRAP, ORDER_CHOICES, ORPHANS_CHOICES,
+    OUTLINE_COLOR_CHOICES, OUTLINE_STYLE_CHOICES, OUTLINE_WIDTH_CHOICES,
+    OVERFLOW_CHOICES, PADDING_CHOICES, PAGE_BREAK_AFTER_CHOICES,
+    PAGE_BREAK_BEFORE_CHOICES, PAGE_BREAK_INSIDE_CHOICES, POSITION_CHOICES,
+    QUOTES_CHOICES, ROW, SEPARATE, SHOW, SIZE_CHOICES, STATIC, STRETCH,
+    TABLE_LAYOUT_CHOICES, TEXT_ALIGN_CHOICES, TEXT_DECORATION_CHOICES,
+    TEXT_INDENT_CHOICES, TEXT_TRANSFORM_CHOICES, TOP, TRANSPARENT,
+    UNICODE_BIDI_CHOICES, VISIBILITY_CHOICES, VISIBLE, WHITE_SPACE_CHOICES,
+    WIDOWS_CHOICES, WORD_SPACING_CHOICES, Z_INDEX_CHOICES, OtherProperty,
+    TextAlignInitialValue, default,
 )
 from .exceptions import ValidationError
-from .wrappers import Border, BorderBottom, BorderLeft, BorderRight, BorderTop, Outline
+from .wrappers import (
+    Border, BorderBottom, BorderLeft, BorderRight, BorderTop, Outline,
+)
 
 _CSS_PROPERTIES = set()
 
@@ -304,7 +305,7 @@ def __init__(self, **style):
     max_height = validated_property('max_height', choices=MAX_SIZE_CHOICES, initial=None)
 
     # 10.8 Leading and half-leading
-    # line_height
+    line_height = validated_property('line_height', choices=LINE_HEIGHT_CHOICES, initial=NORMAL)
     # vertical_align
 
     # 11. Visual effects #################################################