Various test structures and methods for monitoring or controlling a semiconductor fabrication process are provided. One test structure formed on a wafer as a monitor for a lithography process includes a bright field target that includes first grating structures. The test structure also includes a dark field target that includes second grating structures. The first and second grating structures have one or more characteristics that are substantially the same as one or more characteristics of device structures formed on the wafer. In addition, the test structure includes a phase shift target having characteristics that are substantially the same as the characteristics of the bright field or dark field target except that grating structures of the phase shift target are shifted in optical phase from the first or second grating structures. One or more characteristics of the targets can be measured and used to determine parameter(s) of the lithography process.