The information literacy (IL) assessment program at Manhattan College in Riverdale, New York, instituted in 2014-2015, evaluates students' information literacy capabilities as demonstrated in their written coursework, their test performance, and their comments on library instruction sessions. Both instruction and assessment are closely linked to five learning objectives, and five years' assessment results have led to significant changes in the IL instruction program. This paper presents key concepts in IL assessment; highlights the importance of evidence-based measures (that is, direct assessment of cognitive outcomes); describes Manhattan College's three assessment methods, with guidelines for the reporting of results; discusses sampling difficulties and related statistical issues; describes the changes in IL instruction undertaken in response to the results ("closing the loop"); and reviews additional assessment methods that can help demonstrate the impact of IL instruction on broader educational outcomes.