A quantitative microplankton counting procedure is described which involves: 1) obtaining percent composition data by examining a drop of concentrate with a regular slide and coverslip, 2) obtaining cell density data for a selected organism using the Lackey drop count method, and 3) calculating density data for the remainder of the organisms from 1 and 2. Where detailed statistical analysis is not available or is not warranted, the procedure gives adequate precision and some saving of counting time.