The National Committee on Science Education Standards and Assessment (1994 draft) viewed several science processes as important to an understanding of science as inquiry: formulating usable questions, planning experiments, conducting systematic observations, interpreting and analyzing data, drawing conclusions, communicating, and coordinating and implementing a full investigation. This study is one of three undertaken to develop research rubrics for a performance assessment of science processes and to evaluate seventh-grade science students' ability to perform them. Specifically, this article focuses on the processes of recording data, analyzing data, drawing conclusions, and providing evidence. A total of 364 students field tested the Alternative Assessment of Science Process Skills. Their responses were used to develop a research rubric, and then this rubric was used to determine response patterns that could inform both instruction and assessment of science process skills. Only 61% of students performed the activity and recorded data successfully. Sixty-nine percent of students did not attend to the hypothesis in drawing their conclusions. Eighty-one percent did not provide specific evidence for their conclusions. These results were discussed in light of relevant theories and models as well as their implications for instruction and assessment.