The Paul-G. Siebel Papers contain correspondence, memoranda, speeches, and other documents spanning the years 1968 to 1975. The bulk of the material in the collection dates from Siebel's tenure as Geschäftsführer (General Manager) of J.Walter Thompson's Frankfurt Office from 1969 through 1975. The Siebel Papers mostly concern relations with the advertising industry. As media director of JWT Frankfurt (a position he held simultaneously with that of Geschäftsführer), Siebel corresponded with members of the industry as well as the media; as JWT Frankfurt's representative to organizations such as the GWA (Gesellschaft der Werbeagenturen [Association of Advertising Agencies]), he attended meetings within the industry and discussed a variety of advertising and political subjects. Other topics documented in the collection include media planning, account direction, production of advertisements, and business management JWT Frankfurt. The Organizations Series, relating to Siebel's participation in advertising groups, comprises one-half of the collection. Other series include the Non-Frankfurt JWT Offices; Correspondence; Memoranda/Haus-Mitteilungen; Clients; Media; Other JWT Frankfurt Departments; Euuropean Media Manager; and Organizations Series. The majority of items in the collection, approximately 80 percent, are in the German language, with the remainder in English.

The Non-Frankfurt JWT Offices Series consists of correspondence and other documents pertaining to over 20 international offices of J. Walter Thompson. Offices in London, New York, Tokyo, and Brussels make up the bulk of the series. Topics mentioned include: a European advertising campaign for the Quebec Government; media recommendations (both in Brussels folder); market research on home financing in Germany; German regulation of alcohol advertising (both in London folder); and the importance of appropriate broadcast times for television ads (Vienna folder). The London folders contain substantial material on the "Target Group Index" (T.G.I.), including numerous articles and brochures by Timothy Joyce and Jack Fothergill of the British Market Research Bureau (BMRB). JWT correspondents in the series include Albert Brouwet and Arlette Hill of JWT Brussels; Peter Gilow, head of JWT Frankfurt; William D. Thurber of JWT Johannesburg; Elvira Bruhnsen, Jeremy Bullmore, Alec Morrison, Neil Walker, and David Wheeler of JWT London; Harry Clark and Don Johnston of JWT New York; Tom Sutton of JWT Tokyo; and René Müller of JWT Zurich. The language of the series is predominantly English (approximately 80 percent), with the remainder in German.

The Correspondence Series contains Siebel's general business and personal correspondence. Topics mentioned in the series include buying advertising space and placing print advertisements, Siebel's 1969 appointment to the position of General Manager (Hauptgeschäftsführer) and Media Director, and the 1969 "Kongress der Werbung" held in Munich. Specific items in the series include 1971 ad copy featuring Siebel's endorsement of "Jasmin" magazine, produced by competitor Heumann, Ogilvy and Mather; and the 25th anniversary edition of the "NRZ" ( ) newspaper. Siebel's correspondents in the series primarily include representatives of the advertising departments of various newspapers and magazines as well as members of media and marketing research organizations. Individual correspondents include H.-J. Artopé of Burda Verlag, Peter Baltzer of Carl Gabler Werbe GmbH, Rolf Günther of Gruner and Jahr Verlag, Karl Hartner of Herr Jenetzky of Fritz Busche Druckerei GmbH, and Gerd Springer of the The language of the series is predominantly German (ca. 90%), with the remainder in English.

The Memoranda/Haus-Mitteilungen Series contains memoranda, newsletters, and other documents relating to the policies and daily operations of JWT Frankfurt, JWT's international organization, and the Media Department. Contains a list of the year's TV spots produced by JWT in 1973, and a memo (late 1960's or early 1970's) advocating the use of psychological consultants for the production of ads in Frankfurt, as was already the practice in New York and London. In this series, folders originally labelled "JWT Intern" and "Organisation JWT" have been combined into one series. The language of the series is predominantly German, with the remainder in English.

The Clients Series contains correspondence, memoranda, contact reports and other documents pertaining to clients and their media needs. Topics mentioned in the series include: the production and placement of television and radio advertisements; contract negotiations and clarifications; forms of agency compensation; and an anti-drug public relations campaign. Correspondents include: various representatives of media firms such as the BBC, BILD, Burda, and Gruner and Jahr; client company executives such as W. Schmittel of Braun and H. Woyzik of Ciba Geigy; and JWT personnel such as David Campbell-Harris (JWT Milan), Wally O'Brien (JWT Chicago), and Manfred Süß (Media head, JWT Frankfurt). The language of the series is predominantly German (ca. 80%) with the remainder in English.

The Media Series contains guidelines for advertising testing, a lengthy 1966 index of trade literature called "99 Books for the Mediaman," and reports on Siebel's visits to daily regional newspaper offices. Specific items in the series include an ad recognition and impact test ("Anzeigenkompass") from 1971. The language of the series is exclusively German.

The Other JWT Frankfurt Departments Series contains documentation of "adjoining" ("flankierende") departments at JWT-Frankfurt. Departments documented in the series include: Media Planning, Production, Administration, Art Buying, Art Service, Sound and Film Studios, Test Kitchen, Translation, FFF (JWT's own production company), and Pen Pool. The language of the series is entirely German.

The European Media Manager Meeting Series contains correspondence, speeches, and other documents pertaining to the 1973 European Media Manager Meeting in Madrid. The series is made up largely of correspondence with JWT international office media directors with their suggestions for planning the meeting's agenda, and their evaluations of the meeting's effectiveness afterward. Among the offices participating were Amsterdam, Copenhagen, Frankfurt, Helsinki, Madrid, Milan, New York, Stockholm, Toronto, Vienna, and Zurich. JWT international correspondents include Julian Bravo (Madrid), Elvira Bruhnsen (London), Joop Halsema (Amsterdam), and David Wheeler (London). Topics mentioned in the series include 1974 plans for publishing a "European Media Booklet" for international JWT's; the switch from a media-marketing to an account-planning approach at JWT Amsterdam; and international models for television coverage and frequency distribution. Specific items in the series include product test case histories for Germany, a Dick Jones speech on "The Concept of Effective Reach," and statistical data on media audiences in Spain. Clients mentioned in the series include Brinkmann, Ford, Kraft, Kodak, Jacobs, Pan Am, Pepsi, and Singer. The language of the series is predominantly English (approximately 75 percent) with the remainder in German.

The Professional Advertising Organizations Series contains material pertaining to professional organizations with which Siebel had contact. These organizations include the GWA-GIW (GWA-Institut fur Wirtschaftlichkeit in der Werbung [GWA-Institute for Economic Efficacy in Advertising]) and ZAW (Zentralausschuß der Werbewirtschaft [Central Committee of the Advertising Industry]). The series contains information on women in advertising, public service advertising, and a great deal of information on the regulation of advertising to children in Germany. Specifically mentioned in the series are issues related to alcohol and automobile advertising, the introduction of "Feuersteins" (Flintstones) products for children in the Federal Republic, and professional seminars for advertising executives. Clients mentioned in the series include Buer, Elida Gibbs, Glücksklee, Jacobs, Kellog, Kraft, Lever Sunlicht, Pepsi, and Wick. The language of the series is predominantly German.