EXHIBIT 31.1
 CERTIFICATIONS
  1.
    
    I have reviewed this annual report of Concho Resources Inc. (the Registrant);2.
    
    Based on my knowledge, this annual report does not contain any untrue statement of a material
fact or omit to state a material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading with respect to the period
covered by this annual report;3.
    
    Based on my knowledge, the financial statements, and other financial information included in
this annual report, fairly present in all material respects the financial condition, results
of operations and cash flows of the Registrant as of, and for, the periods presented in this
annual report;4.
    
    The Registrants other certifying officer and I are responsible for establishing and
maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and
15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules
13a-15(f) and 15d-15(f)) for the Registrant and have:
 (a)
    
    Designed such disclosure controls and procedures or caused such
disclosure controls and procedures to be designed under our supervision, to ensure
that material information relating to the Registrant, including its consolidated
subsidiaries, is made known to us by others within those entities, particularly
during the period in which this report is being prepared;(b)
    
    Designed such internal control over financial reporting, or caused such
internal control over financial reporting to be designed under our supervision, to
provide reasonable assurance regarding the reliability of financial reporting and
the preparation of financial statements for external purposes in accordance with
generally accepted accounting principles;(c)
    
    Evaluated the effectiveness of the Registrants disclosure controls and
procedures and presented in this report our conclusions about the effectiveness of
the disclosure controls and procedures, as of the end of the period covered by this
report based on such evaluation; and(d)
    
    Disclosed in this report any change in the Registrants internal control
over financial reporting that occurred during the Registrants fourth fiscal quarter
that has materially affected, or is reasonably likely to materially affect, the
Registrants internal control over financial reporting; and
 5.
    
    The Registrants other certifying officer and I have disclosed, based on our most recent
evaluation of internal control over financial reporting, to the Registrants auditors and the
audit committee of Registrants board of directors (or persons performing the equivalent
functions):
 (a)
    
    All significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are reasonably likely
to adversely affect the Registrants ability to record, process, summarize and
report financial information; and(b)
    
    Any fraud, whether or not material, that involves management or other
employees who have a significant role in the Registrants internal control over
financial reporting.
 Date: February 26, 2010
    /s/  Timothy A. LeachTimothy A. LeachDirector, Chairman of the Board of Directors, Chief Executive Officer and President (Principal Executive Officer)