Hydroacoustic sampling is a common and useful tool for the assessment of aquatic and marine organisms.  Technological and theoretical improvements are consistently occurring, but comparability of data from different environments is often limited (or perceived to be limited) by differences in equipment, sampling, and data analysis techniques.  While some effort has been made to identify factors that impart incomparability and to develop/adopt standards to minimize differences, uncertainties remain.  We propose a symposium to review and synthesize the need for and importance of standardization in hydroacoustic assessment.  Our primary objective is to identify areas in which standardization efforts remain necessary and critical to improve comparability of research.  We invite presentations from aquatic and marine environments that compare and contrast multiple methods of assessing organisms and communities using hydroacoustics.  Examples of topics include comparisons of frequencies, equipment, software, deployment techniques, and density apportionment to species or size groups.