Algae and Algal Carbonates are of interest to geo- and bioscientists because of the significant interactions between algal life and environ- ment. Much information about systematical, morphological and eco- logical data of fossil algae has been accumulated during the last two decades. Facies interpretation, sedimentology, and biostratigraphic correlations, as well as speculations about Precambrian ecosystems have received new impulses from the detailed study of Recent algae and their fossil counterparts. During the First International Symposium on Fossil Algae, orga- nized by the Institute of Paleontology of the University Erlangen- Niirnberg in October 1975, about 130 scientists were able to discuss the present status of knowledge; 55 lectures were given, 37 of which now have been chosen for publication. Some of these articles comprehend fundamental reviews on algal groups and algal constructions, such as Monty on the stromatolites, Herak et al. and the French Group on the dasyclads, and Wray and Poignant on the Paleozoic and Mesozoic red algae. Other articles deal with the biology and morphology of blue-green algae, with the arduous problem of the affinities of many algae and pseudo-algae , with bio- metrical methods and with the ultrastructure of calcareous algae. A broad section of this book is reserved for some stimulating papers about the role of algae as facies indicators and sedimentological factors in Recent and Ancient environments. Thanks to the gratefully accepted co-operation of many collegues, we hope this book may offer a good cross-section through main trends of recent algal research.