Researchers and clinicians wishing to assess anxiety must choose from among numerous assessment options, many of which purport to measure the same or a similar construct. A common reporting metric would have great value and can be achieved when similar instruments are administered to a single sample and then linked to each other to produce cross-walk score tables. Using item response theory (IRT), we produced cross-walk tables linking three popular "legacy" anxiety instruments--MASQ (N=743), GAD-7 (N=748), and PANAS (N=1120)--to the anxiety metric of the NIH Patient Reported Outcomes Measurement Information System (PROMIS(®)). The linking relationships were evaluated by resampling small subsets and estimating confidence intervals for the differences between the observed and linked PROMIS scores. Our results allow clinical researchers to retrofit existing data of three commonly used anxiety measures to the PROMIS Anxiety metric and to compare clinical cut-off scores.