EXHIBIT 5.1

EXHIBIT 5.1


September 14, 1999


AvalonBay Communities, Inc.
2900 Eisenhower Avenue, Suite 300
Alexandria, Virginia 22314

Re: Legality of Securities to be Registered
under Registration Statement on Form S-3

Ladies and Gentlemen:

This opinion is furnished in connection with the registration on
Form S-3 (the "Registration Statement"), pursuant to the Securities Act of
1933, as amended (the "Securities Act"), which relates to the possible sale
from time to time of up to 267,553 shares (the "Redemption Shares") of common
stock, par value $.01 per share ("Common Stock"), of AvalonBay Communities,
Inc., a Maryland corporation (the "Company"), by holders of units of limited
partnership interest ("Units") in Bay Pacific Northwest, L.P., a Delaware
limited partnership (the "Partnership"), of which the Company is the sole
general partner. The holders of the Units may receive the Redemption Shares
(together with rights to purchase shares of Series E Junior Participating
Cumulative Preferred Stock, par value $.01 per share, which are attached to
all shares of Common Stock) upon the tender of such holder's Units to the
Partnership for redemption if the Company exercises its right pursuant to the
Partnership's Agreement of Limited Partnership, as amended (the "Partnership
Agreement"), to issue the Redemption Shares in exchange for such tendered
Units. The Registration Statement provides that the Redemption Shares may be
offered from time to time by the selling stockholders, at prices and on terms
to be determined at the time of sale and to be set forth in one or more
prospectus supplements (each a "Prospectus Supplement") to the prospectus
contained in the Registration Statement to the extent required by law.

In connection with rendering this opinion, we have examined (i) the
charter of the Company, as amended to the date hereof and on file with the
Maryland State Department of Assessments and Taxation; (ii) the bylaws of the
Company, as amended to the date hereof; (iii) the Partnership Agreement; (iv)
such records of the corporate proceedings of the Company as we deemed material;
(v) the Registration Statement and the exhibits thereto; and (vi) such other
certificates, receipts, records and documents as we considered necessary for the
purposes of this opinion. In our examination, we have assumed the genuineness of
all signatures, the legal capacity of natural persons, the authenticity of all
documents submitted to us as certified, photostatic or facsimile copies, the
authenticity of the originals of such copies and the authenticity of telephonic
confirmations of public officials and others. As to facts material to our
opinion, we have relied upon certificates or telephonic confirmations of public
officials and certificates, documents, statements and other information of the
Company or representatives or officers thereof.





AvalonBay Communities, Inc.
September 14, 1999
Page 2

We are attorneys admitted to the practice of law in the Commonwealth of
Massachusetts. We express no opinion concerning the laws of any jurisdictions
other than the laws of the United States of America and the Maryland General
Corporation Law, and also express no opinion with respect to the blue sky or
securities laws of any state, including Massachusetts and Maryland.

Based upon the foregoing, we are of the opinion that under the Maryland
General Corporation Law, when the Registration Statement relating to the
Registered Shares has become effective under the Securities Act and the
Redemption Shares have been duly issued in exchange for Units tendered to the
Partnership for redemption in accordance with the provisions of the Partnership
Agreement, such Redemption Shares will be validly issued, fully paid and
nonassessable.

The foregoing assumes that all requisite steps will be taken to comply
with the requirements of the Securities Act and applicable requirements of state
laws regulating the offer and sale of securities.

We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to us with respect to this opinion
under the heading "Legal Matters" in the Prospectus which is a part of such
Registration Statement.


Very truly yours,

/s/ Goodwin, Procter & Hoar LLP

GOODWIN, PROCTER & HOAR LLP