ABSTRACT Experimental dissolution of Globigerinoides ruber , Globigerinoides trilobus , Globorotalia menardii , and Orbulina universa from core top sediments in the Caribbean Sea are being conducted by reaction with a sodium acetate-acetic buffer solution of pH 6.1 at atmospheric pressure and room temperature. Preliminary results suggest that the foraminifera tests are attacked by the solution primarily from the outside surface such that layers of calcite are successively destroyed. SEM micrographs of successively “stripped” layers indicate that a finely crystalline, smooth layer forms the outer shell and that a more coarsely crystalline layer underlies this surface layer. Ca/Mg analysis of the buffer solutions after successive intervals of dissolution indicate that the calcite dissolving first is richer in Mg than the calcite which dissolves last. δO 18 concentrations of undissolved and dissolved tests are not significantly different. Dissolution of foraminifera in size fractions greater and less than 250 microns indicates that the small-size fraction dissolves significantly faster than the coarser one. These laboratory results are compatible with observations of the selective dissolution of foraminifera in Caribbean core P6304-8.