Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  Jones Mark R
 2. Date of Event Requiring Statement (Month/Day/Year)
03/08/2018		 3. Issuer Name and Ticker or Trading Symbol
CoreSite Realty Corp [COR]
(Last)
(First)
(Middle)
C/O CORESITE REALTY CORPORATION, 1001 17TH STREET, SUITE 500		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Chief Accounting Officer
 5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

DENVER, CO 80202		 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 14,260 (1)
D
 

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Jones Mark R
C/O CORESITE REALTY CORPORATION
1001 17TH STREET, SUITE 500
DENVER, CO 80202		       Chief Accounting Officer  

Signatures

/s/ Derek S. McCandless, Attorney-in-Fact 03/19/2018
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Includes 5,613 shares of unvested restricted stock awards granted to the reporting person under the issuer's 2010 Equity Incentive Award Plan. The unvested shares of restricted stock vest as follows: (i) 1,169 shares vest on March 3, 2019, (ii) 2,134 shares vest in two equal annual installments on March 2, 2019 and March 2, 2020, and (ii) 2,310 shares vest in three equal annual installments on March 8, 2019, March 8, 2020, and March 8, 2021, in each case provided that the reporting person remains in continuous service with the issuer as of each vesting date.

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