What is... a Partlet?

The partlet covers the area between the dress and the neck - basically covering the chest and shoulders - to varying degrees and ties under the arms.
It could be used in varying ways, either to make things more modest, or to make things veiled and enticing.
The partlet either gathers to a tight band at the neck, or lays flat with only the front two or three inches gathered to the neckband. In either case, it opens at the front, where the neckband is fastened together with laces, or hooks and eyes.
Earlier versions of the partlett include: a scapula

The partlet dates from the Tudor and Elizabethan period (England, 1500 - 1600) and Flemish working-class women 1550s - 1570.
The original garment was intended for warmth, but by the mid 16th century, it'd purpose was purely decorative, and thus it was made from very light weight materials.

• The Renaissance Artitist's About the partlet
• sempstress.org's 1570s Middle class description
• Bronzino's (1503-1572) Portrait of a Young Girl with a Prayer Book
• Portrait of a Young Woman by an unknown Netherlandish Painter, c. 1535

• The Renaissance Artitist's Partlet construction
• Drea Leed's Partlet Instructions
• Simplicity Pattern 8881 - see more detail
• Margo Anderson's The Elizabethan Lady's Underpinnings