Abstract: A hair weft for increasing the apparent length and/or bulk of a user's hair includes an elongate arcuate thin flexible substrate which carries stands of hair or hair-like filaments over substantially its entire surface area. The substrate is free of apertures or holes, so that within its perimeter the entire surface area of the substrate carries hair strands. And, because of the large number of hair strands carried by the hair weft, only a single application of one hair weft will be satisfactory to achieve the desired effect in most cases. The weft is applied adhesively to underlying human hair, and conceals the adhesive while adding substantial bulk and/or length to the hair for the wearer. The substrate of the hair weft serves as an adhesive carrier during application of the hair weft to a wearers head, so that a relatively unskilled user can achieve an attractive result, even at home without the skills of a stylist of cosmetician.