The use of peer assessment (PA) as an alternative form of evaluation method is reported to be helpful in learning and is increasingly being adopted in higher education settings. Through collecting data from 280 university students in Taiwan, a 20-item instrument was developed to investigate university students' attitudes toward and perceptions of PA and online PA. Four subscales, Positive Attitudes, Online Attitudes, Understanding-and-Action, and Negative Attitudes, were extracted and reliabilities were calculated. Results revealed that participating students held positive attitudes toward the use of PA activities, but they viewed online PA as a technical tool to facilitate assessment processes, rather than as a learning aid. Male students had more positive attitudes toward PA than females did, and students with previous PA experiences had less negative attitudes toward PA. A majority of these students suggested that the PA score should be counted as a small part of the total course grade, and there was an effect of the perceived importance of PA score on students' attitudes toward these four subscales.