This report describes the development of a Literacy Assessment Battery (LAB) for determining the relative efficiency with which adults can comprehend language by reading or listening. Development of the LAB included: the tryout with adults of two listening and reading tests designed for children; experimental studies of a decoding task involving simultaneous listening and reading; a calibration study to develop listening and reading passages of comparable difficulty; and a small-scale study to demonstrate how the experimental LAB might be normed and interpreted to make it an operational instrument. The LAB and the LAB examiner's manual are included. (Author/BW)