EXHIBIT 5.1

                  [Letterhead of Simpson Thacher & Bartlett]


                                                July 31, 1998



GRAHAM PACKAGING COMPANY
GPC CAPITAL CORP. I
GRAHAM PACKAGING HOLDINGS COMPANY
1110 East Princess Street
York, Pennsylvania  17403

Ladies and Gentlemen:

               We have acted as special counsel to Graham Packaging Company, a
Delaware limited partnership (the "Operating Company"), GPC Capital Corp. I, a
Delaware corporation ("Capco I" and, together with the Operating Company, the
"Company Issuers"), Graham Packaging Holdings Company, a Pennsylvania limited
partnership ("Holdings"), and GPC Capital Corp. II, a Delaware corporation
(together with the Company Issuers and Holdings, the "Issuers"), in connection
with the Registration Statement on Form S-4, (File No. 333-53603) (the
"Registration Statement") filed by the Issuers with the Securities and
Exchange Commission (the "Commission") under the Securities Act of 1933, as
amended (the "Securities Act"), relating to, among other things, the issuance
by the Company Issuers of $150,000,000 aggregate principal amount of their 8
3/4% Senior Subordinated Notes Due 2008, Series B (the "Fixed Rate Senior
Subordinated Exchange Notes") and $75,000,000 aggregate principal amount of
their Floating Interest Rate Term Securities Due 2008, Series B (the "Floating
Rate Senior Subordinated Exchange Notes" and, together with the Fixed Rate
Senior Subordinated Exchange Notes, the "Senior Subordinated Exchange Notes").



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               The Fixed Rate Senior Subordinated Exchange Notes and the
Floating Rate Senior Subordinated Exchange Notes will be offered by the
Company Issuers in exchange (the "Senior Subordinated Exchanges") for
$150,000,000 aggregate principal amount of their outstanding 8 3/4% Senior
Subordinated Notes Due 2008, Series A (the "Fixed Rate Senior Subordinated Old
Notes") and $75,000,000 aggregate principal amount of their outstanding
Floating Interest Rate Term Securities Due 2008, Series A (together with the
Fixed Rate Senior Subordinated Old Notes, the "Senior Subordinated Old
Notes"), respectively. The Senior Subordinated Old Notes are unconditionally
guaranteed (the "Old Guarantees") by Holdings on a senior subordinated basis,
and Holdings will unconditionally guarantee (the "Holdings Guarantees") the
performance and payment of the obligations of the Company Issuers under the
Senior Subordinated Exchange Notes. Accordingly, as part of the Senior
Subordinated Exchanges, Holdings will issue the Holdings Guarantees in exchange
for the Old Guarantees. The Senior Subordinated Old Notes were, the Senior
Subordinated Exchange Notes will be and the Holdings Guarantees will be, issued
under an Indenture dated as of February 2, 1998 (the "Senior Subordinated
Indenture") by and among the Company Issuers, Holdings, as guarantor, and United
States Trust Company of New York, as trustee (the "Senior Subordinated
Trustee").
               We have examined the Registration Statement and the Senior
Subordinated Indenture, which has been filed with the Commission as an exhibit
to the Registration Statement. In addition, we have examined, and have relied
as to matters of fact upon, originals or copies, certified or otherwise
identified to our satisfaction, of such corporate



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records, agreements, documents and other instruments and such certificates or
comparable documents of public officials and of officers and representatives
of the Company Issuers, and have made such other and further investigations,
as we have deemed relevant and necessary as a basis for the opinions
hereinafter set forth.
               In such examination, we have assumed the genuineness of all
signatures, the legal capacity of natural persons, the authenticity of all
documents submitted to us as originals and the conformity to original
documents of all documents submitted to us as certified or photostatic copies,
and the authenticity of the originals of such latter documents.
               Based upon the foregoing, and subject to the qualifications and
limitations stated herein, we are of the opinion that, assuming that the
Senior Subordinated Indenture constitutes a valid and legally binding 
obligation of the Senior Subordinated Trustee, when (i) the Senior Subordinated 
Indenture has been duly qualified under the Trust Indenture Act of 1939, 
as amended, 



GRAHAM PACKAGING COMPANY, ET AL.         -4-                      July 31, 1998

and (ii) the Senior Subordinated Exchange Notes have been duly executed and
issued by the Company Issuers and duly authenticated and delivered by the Senior
Subordinated Trustee in accordance with the provisions of the Senior
Subordinated Indenture upon the Senior Subordinated Exchanges and (iii) the
Holdings Guarantees have been duly executed and issued by Holdings under the
laws of the Commonwealth of Pennsylvania, the Senior Subordinated Exchange 
Notes will constitute valid and legally binding obligations of the Company 
Issuers, and the Holdings Guarantees will constitute valid and legally binding 
obligations of Holdings.
               Our opinions set forth in the preceding sentence are subject to
the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization,
moratorium and other similar laws relating to or affecting creditors' rights
generally, general equitable principles (whether considered in a proceeding in
equity or at law) and an implied covenant of good faith and fair dealing. 
               We express no opinion as to the validity, legally binding
effect or enforceability of any provision of the Senior Subordinated
Registration Rights Agreement




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(as defined in the Registration Statement) or any provision of the Senior
Subordinated Indenture that requires or relates to payment of any interest at
a rate or in an amount which a court would determine in the circumstances
under applicable law to be commercially unreasonable or a penalty or a
forfeiture.
               Insofar as the opinions expressed herein relate to, or are
dependent on matters governed by, the laws of the Commonwealth of
Pennsylvania, we have relied upon the opinion of Morgan, Lewis & Bockius LLP,
filed as Exhibit 5.2 to the Registration Statement.
               We are members of the Bar of the State of New York and we do
not express any opinion herein concerning any law other than the law of the
State of New York, the federal law of the United States, the General
Corporation Law of the State of Delaware, the Revised Uniform Limited
Partnership Act of the State of Delaware, the Limited Liability Company Act of
the State of Delaware, including decisions of the Delaware courts interpreting
the foregoing Delaware statutes, and, to the extent set forth herein and in
reliance upon the aforesaid opinion of Morgan, Lewis & Bockius LLP, the laws of
the Commonwealth of Pennsylvania.
 
               We hereby consent to the use of this opinion letter as Exhibit
5.1 to the Registration Statement and to the use of our name under the caption
"Legal Matters" in the Prospectus included in the Registration Statement.

                                             Very truly yours,


                                             /s/ Simpson Thacher & Bartlett


                                             SIMPSON THACHER & BARTLETT