A skin treatment can include applying a microneedle device to a region of the skin so that microneedles of the device penetrate the stratum corneum. The arrangement of microneedles can have first microneedles with a first length and second microneedles with a second length, different from the first length. The first and second microneedles can be formed from a mixture of a polymeric material and an active agent beneficial to skin. After the device is applied to the skin, the first and second microneedles can be released below the skin surface, followed by dissolution of the first and second microneedles.