Parallel Lines is the third studio album by the American rock band Blondie, released in September 1978 by Chrysalis Records. The album reached #1 in the United Kingdom in February 1979 and proved to be the band's commercial breakthrough in the United States, where it reached #6 in April 1979. As of 2008, the album had sold over 20 million copies worldwide.

In geometry, parallel lines are lines in a plane which do not meet; that is, two lines in a plane that do not intersect or touch each other at any point are said to be parallel. By extension, a line and a plane, or two planes, in three-dimensional Euclidean space that do not share a point are said to be parallel. However, two lines in three-dimensional space which do not meet must be in a common plane to be considered parallel; otherwise they are called skew lines. Parallel planes are planes in the same three-dimensional space that never meet.