(scanned by William Stein)
Scroll below the photo for number key and some interesting remarks about the conference. (Thanks to Ken Ribet for sending me the photo and Ribet and Patterson for identifying many people in it.) 
If you think you know the identity of somebody not identified below, please send me an email (was@math.harvard.edu).

Ken Ribet:
These are the famous volumes "Modular Forms in 1 Variable IIV". Some of
the numbers are 349, 350, 476; these
are volumes II, III, IV. I'm
talking about Lecture Notes in Math. There are later volumes (601 and
627) from a conference in Bonn in 1976."
The food and wine were great. My only regret is that I didn't really start learning about wine until after the conference. I have no idea what we were drinking, but I remember that it was great. A lot of the tables had the idea that you could get a second bottle of wine as soon as possible; they (we) did this by draining the first bottle as soon as we sat down. I don't know whether there was a finite supply of wine for the whole group at each meal  but this must have been the case. I really got drunk the last night. They served suckling pig and had Alsatian wine with it. 
Samual J. Patterson: "There are people who were there that I do not recognise on the photo (e.g. Serre, Eichler, Cassels, Kenku, Petersson, Birch, Bombieri, Alan Baker, Curt Meyer, Leutbecher, Oliver Atkin in a totally random order). Perhaps one or another will come to me. The conference was financed very generously by NATO. This was in the middle of the Vietnam war and there was a lot of discomfort and discussion about this fact. One of the uses to which the NATO money was put was there there were about three attractive hostesses in bright yellow dresses. One of these is Nr. 42; I have no idea what her name was. Also the food was excellent  thanks in part to NATO. Some were graduate students who did not continue with mathematics  generally there were a large number of graduate students like myself there  also financed by NATO, to the disgust of the likes of Grothendieck, Langlands and Godement. However it was my first conference and nothing has really lived up to it since then. I profited enormously from it." 
Bill Casselman: Other people missing in the picture are Andy Ogg, Jacques Velu and Robert Langlands. I think there were more than 3 of the hostesses in yellow dresses, who were called "the daffodils" by many. 
Eli N. Donkar: From: "Eli N. Donkar" To: was@math.harvard.edu Date: 04/16/04 11:49 am William, My wife stumbled across this photo on the web because I was (correctly) identified in it. I was a graduate student at Princeton at the time, studying with Shimura. After graduate school I continued in number theory briefly at Johns Hopkins, but ended up switching careers doing financial forecasting for the Social Security Administration for the last 27 years. I have not had time to inspect the picture carefully, but I should be able to come up with a few names of my contemporaries who attended. The one correction I did notice that you should make is for number 70 (sitting on my left). His full name is KuangYen Shih. Shih was my classmate at Princeton and Ph.D. brother (i.e. also a student of Shimura). Boy did it bring back memories. One comment to add to Patterson's memories is that not only was the food out of this world, but the wine was superb (I think Serre and the French contingent had a hand in the selections) and it was very free flowing. A virtual nirvana for a poor graduate student of the time. Although the food and wine were great, the mathematics was even better and we certainly spent many more hours in the day talking and doing mathematics than we spent eating and drinking wine. 
From: Jurgen Elstrodt My former student Olav Richter (Dept. of Math. University of Denton, Texas) drew my attention to the Antwerp Modular Forms 1972 Conference Photo in the Internet. I took part in the conference and I am No. 75 on the Photo (probably S.J. Patterson identified me). My photo of the participants is slightly different from the one in the internet, hence some people can better be identified on my photo. In addition to the names on your list, I can identify the following people: 7. Kenku (Nigeria) 18. Ditters (Netherlands) 19. Hostess Braaksma (?) 20. M. Hazewinkel (Amsterdam) 28 Heinz Helling (Bielefeld, Germany) 29. Horst Günter Zimmer (Saarbrücken, Germany) 30 may be Günter Köhler (Würzburg), but could also be WulfDieter Geyer (Erlangen). I cannot remember to have seen Köhler on the conference. 42. Hostess Rita 45. Oskar Herrman (Heidelberg, Germany) 46. I could not identify this woman when I wrote down my list. According to my list of names (written down from memory immediately after the conferece), the "unidentified woman to the left of Serre between 34 and 37 horizontally" is Yvette Amice (albeit with a questionmark). 57. Stöhr (Berlin, Germany) 66. Meinhard Peters (Münster, Germany) 67. + 68. Assistants to Kuyk Several participants are not on the photo, e.g. Eichler, Cassels, Petersson, Bombieri, Langlands, Curt Meyer, Leutbecher (Munich), Bauermeister (Göttingen), Lange, Cohn. I still have a list of the participants who lived in the students dormitory (with the names of the participants and their rooms). I hope my list will help you to fill some gaps. Best wishes Jürgen Elstrodt 
Subject: 1972 Summer School on Modular Functions From: Willem Kuijk To: was@math.harvard.edu Date: 05/26/04 09:01 am Dear Dr Stein, Thank you for bringing back to my memory all that concerns and concerned the 1972 Antwerp Summer School, that was a most perhaps the most important professional event in my life. It may interest you to know that, before I did a final offer for such a conference to Serre at ICM Nice, I tried out to have several conferences with Serre as star speaker. From that time on we have had a friendly colleagial relationship. Prior to 1967/68 at the IAS where I assisted him writing a "bouquin" as he called it ("abelian ladic representations and elliptic curves") he was at my colloquium at Mc Gill U. and I ventured a few years later in Nice to propose that a big conference on Number Theory should be conducive to changing math. by the turn of the century. To my surprise and pleasure he agreed and he consulted all the leading French mathematicians (Cartier, Poitou, etc but I am sure not Grothendieck) as to what should be a central topic intermediate between all the then extant math fields, so that chances for interdisciplinary results including math. applications (sic) would in due time be most likely. Out came the Modular Function bid, and Serre left me totally free to organize it in my way, which implied I conceived of a friendly environment with relaxation and work and good food and wine. In vino veritas. The work involved cost me more than three years of intensive work including the proceedings. We agreed to not thank Nato too explicitly and friendly in the Proceedings, because we agreed that funding such enterprises should not be a task for a military defense organization. (Nato stopped funding the affair two weeks before the conference began because of protests in the Dutch and French press etc.etc.). I am thankful to you to have made efforts to bring out elements that resulted from the summer school. For so many years now I bear within me a treasure of knowledge regarding the school, but nobody asked me about it; clearly, because I did not belong to the coryphees of the subject. After the school I did what I should do on account of my nature: study physiology, brain physiology and heart ph., foundations of math, educational math. and what have you that I was interested in. I also did exams in philosophy, wrote a 1977 book on "Complementarity in Mathematics", thereby coining the term CIMath. I had only 10 PH.D. students in math among which Jan Denef in Leuven. It was H.W.Lenstra (also a student that I shared with Oort) who wrote in 1994: (forgive me my pride even if L's pronouncement were not true: "without K no 'Antwerp', and without "Antwerp" no solution to the Fermat problem". He referred to the fact that I was called by the Be government when in Princeton to set up a math. dpt at the new university here. I accepted on the condition that they would support and fund a conference in my style on a central math. topic , etc... And I got what I wanted. Seven years ago upon retiring I got a massive aneurysmal brain bleeding and, after two most splendid near death experiences (in which members of the SuSchool and McGill staff + students figured prominently) during a week of coma, I got up and (limpingly though) running again. Ever since I study 6 hours a day, but cannot very easily go to places. Here is the c.v. I wrote. it is somewhere on the net where my name is KuijkGruenbauer to honour my mother and and the memory of her family. Willem KuijkGrünbauer (former name Willem Kuyk) studied Pure Mathematics and Theoretical Physics in Amsterdam and gained a D.Sc. degree with a doctoral thesis in Number Theory and Galois Theory, only with the wish to return to working in Applied Mathematics and the foundations of Physics later on. When employed by the Mathematical Centre in Amsterdam, Canadian job propositions guided him by way of a postdoctorate fellowship into an Associate professorship at McGill University in Montreal, that lasted eight years and ended with the decision to accept an offer by the Belgian Government to set up a department of Mathematics at the new Antwerp University. This decision jibed with his earlier proposal, made during a visiting membership at the IAS (Princeton) to JP. Serre of the Collège de France, to bring all the world's leading Number theorists and their Ph.D. students together into one Summer School, and then see what happens in the way of a rejuvenation of the number theoretic branches of Mathematics. This three week School by the name 1972 Antwerp Summer School on Modular Functions in one variable (with four Springer LNM proceedings) marked the beginning of the Mathematics department at Antwerp University, and, more importantly, it has been a stimulus to many old schools in Number Theory as well as to the establishment of new ones; to the point where it has been conducive to the solution of a series of longstanding conjectures such as de Fermat's Last Theorem, the Weil conjectures etc. Early retirement from the pure Mathematics area finally freed Kuyk's way to take up his interest in regulation systems in Biology (body heat and heart control) and the foundation of Physics (wave equations and questions regarding physical dimensions and the quantum theory of motion). Thanks for listening, Willem 
From: Rob van der Waall To: was@math.harvard.edu Date: 06/02/04 07:08 am Dear William Stein, Yes, I visited the congress on Modular Forms at Antwerp in 1972, and I am identified correctly on the photograph. I can add two persons wanted: 39: Marc Best (an expert in algebraic coding theory; among other things, he did classify all the perfect codes over any alphabeth not only prime powers (up to one small isolated case,later done by Hu if I am not mistaKen); affiliated with the Technical University of Twente, The Netherlands; died by his own hand about 16 years ago); 82: D.C. van Leijenhorst (now at the Catholic University of Nijmegen,The Netherlands) 38 is not Bill Casselmann, as far as I can remember; William, I do not remember your face, unfortunately, About the conference: it was a phantastic experience to me, and to all attendencies I suppose. Best regards, Robert van der Waall ( now at The University of Amsterdam). 