A sensor for monitoring wetness in a diaper or other absorbent article includes a housing that attaches to the absorbent article. The sensor may include inner and outer housing portions that capture an edge of the absorbent article between the housings. The sensor may include contacts that electrically connect with a pair of contact strips embedded in the absorbent article. The distance between the embedded strips may vary depending on the size of the absorbent article. The sensor may include multiple pairs of contacts that are spaced apart to match the distance between the contact strips for the variously sized absorbent articles. In this way, depending on the pair of contacts connected to the contact strips, the sensor may indicate the size of the absorbent article. The sensor may have a housing with a cavity and a lid that closes the cavity. The lid may be secured with a latch.