I'd say this was probably taken in the latter 1910s or early 1920s - right on the cusp of fashions changing from Edwardian to flapper. I hate to disagree with China, but I don't think the hair is a bob per se. I think it's just tucked up and to the back. I'm not sure what the exact name for it is, but I believe it was a vogue hairstyle between the Gibson Girl pompadour and the finger wave. I'd also say that the top of the dress appears to be from around this time frame as well.