The male has a black forehead, wings and tail in summer with a white rump. The rest of the body is bright yellow. The female has rather olive plumage in summer with dull yellow on face and breast. In winter, both sexes are nearly identical. The plumage becomes olive-brown above and buff below. Wings and tail remain black. It measures about 11 centimeters and weighs about 11 grams, which is the average weight of a strawberry! It has a wingspan of 21 cm. He lives up to 8 years.

This bird is a seed eater! It loves thistle, dandelion and sunflower seeds! The male American Goldfinch feeds the female while she incubates the eggs, much like he feeds a baby bird. The female builds the nest. The male may occasionally help her find materials, but he does not help with construction. The American Goldfinch moults in the spring. This is when the male puts on his nuptial plumage!