Simplicity 4920 vintage sewing pattern, dated 1963.

Misses' One-Piece Dress:

The princess line dress has a lowered round neckline, inverted pleats at lower edges of side front and side back seams, a button-and-loop closing at center back neck edge, and a zipper closing in left side seam. V. 1 has short set-in sleeves and pockets with button trim. V. 2 is sleeveless and has bow trim. V. 3 is sleeveless and has a self-fabric tie belt. 

Size   18:

Bust   38 inches / 97 cm

Waist 30 inches / 76 cm

Hip     40 inches / 102 cm

Pattern is PRINTED, partly cut and checked complete.  Envelope has significant wear, spotting, split down one side.

More '60s patterns here:

http://allthepreciousthings.com/collections/1960s