The term Chain (sequence) may refer to:

• Chain sequence (continued fraction), numbers in the mathematical study of continued fractions
• Chain of thought, continuous thought process where ideas follow one from the other
• Chain smoking, the habit of smoking continuously
• Chain stitch, in sewing and embroidery, a series of looped stitches that form a chain
• Chain letter, message that attempts to induce the recipient to make a number of copies of the message and then pass them on to one or more new recipients
• Chain, Planetary, a chain of globes serving as fields of evolution in theosophical cosmology
• Crater chain, a line of craters on the surface of an astronomical body
• Daisy chain, originally a garland of flowers, with additional uses in the fields of electronic engineering, computer software, rock climbing, backpacking, fishing, the military, and human relations
• Human chain, a form of protest
• Signifying chain, in semiotics, an interlocking system of signifiers
• Hudson River Chain, one of several chains used in blockades of the Hudson River

Chain may also refer to:

• Archipelago, a chain of islands
• Mountain range, a chain of hills or mountains