United States securities and exchange commission logo

                             March 11, 2021

       Joseph Pergola
       Chief Financial Officer
       Integral Ad Science Holding Corp.
       95 Morton St., 8th Floor
       New York, NY 10014

                                                        Re: Integral Ad Science
Holding Corp.
                                                            Draft Registration
Statement on Form S-1
                                                            Submitted February
12, 2021
                                                            CIK No. 0001842718

       Dear Mr. Pergola:

              We have reviewed your draft registration statement and have the
following comments. In
       some of our comments, we may ask you to provide us with information so
we may better
       understand your disclosure.

              Please respond to this letter by providing the requested
information and either submitting
       an amended draft registration statement or publicly filing your
registration statement on
       EDGAR. If you do not believe our comments apply to your facts and
circumstances or do not
       believe an amendment is appropriate, please tell us why in your

             After reviewing the information you provide in response to these
comments and your
       amended draft registration statement or filed registration statement, we
may have additional

       Draft Registration Statement on Form S-1 filed February 12, 2021

       Prospectus Summary
       Our Sponsor, page 8

   1.                                                   Please include a
summary of the material terms of the director nomination agreement that
                                                        provides Vista the
right to designate all of the nominees for election to your board of
                                                        directors for so long
as Vista beneficially owns 40% or more of the total number of shares
                                                        of your common stock.
Please file the agreement as an exhibit.
       Summary Consolidated Financial Data, page 13

   2.                                                   Please revise here, and
in the Selected Consolidated Financial Data, to present the most
                                                        directly comparable
GAAP measure to your non-GAAP measure of Adjusted EBITDA
 Joseph Pergola
Integral AdLastNameJoseph
            Science Holding Pergola
March      NameIntegral Ad Science Holding Corp.
       11, 2021
March2 11, 2021 Page 2
FirstName LastName
         margin with equal or greater prominence. Refer to Question 102.10 of
the non-GAAP
Risks Related to Being a Public Company
We have identified material weaknesses..., page 46

3.       Please revise to clarify what remains to be completed in your
remediation plan, if
         anything. Also, if the material weakness has not been fully
remediated, revise to disclose
         your estimate of how long it will take to complete your plan and
disclose any material
         costs you have, or expect to be, incurred.
We are an "emerging growth company" and we expect to elect to comply..., page

4.       Please revise to state that because of your election to take advantage
of the extended
         transition provisions for complying with new or revised accounting
standards, your
         financial statements may not be comparable to companies that comply
with public
         company effective dates.
Management   s Discussion and Analysis of Financial Condition and Results of
Operations, page

5.       Please disclose the basis for your claim that you are a leading
digital advertising
         verification company. Please clarify whether the basis for your
leadership is supported by
         quantitative criteria such as market share by revenues or similar
Key Factors Affecting Our Performance, page 75

6.       Please revise to disclose your customer churn for your top 100
customers for all periods
         presented. Also, disclose the percentage of revenue generated from
these customers and to
         the extent such customers do not account for a significant majority of
your revenue, revise
         to also provide churn for your remaining customer base.
Key Business Metrics, page 77

7.       Please revise the net revenue retention disclosures to provide the
percentage of revenue
         generated by your large customers for each period presented. Also,
disclose the net
         revenue retention rate for your other customers to provide context to
this disclosure or tell
         us how you concluded such disclosure was not necessary. In this
regard, we note that
         increasing sales to your existing customer base is a key factor
affecting your
         performance. Refer to Release No. 33-10751.

8.       Please clarify your reference to total "net revenue" in the
calculation of average revenue
         per large customer. Specifically address whether such amount
represents GAAP revenue
         or explain.
9.       You disclose that acquiring new customers, increasing market share and
 Joseph Pergola
Integral AdLastNameJoseph
            Science Holding Pergola
March      NameIntegral Ad Science Holding Corp.
       11, 2021
March3 11, 2021 Page 3
FirstName LastName
         operations internationally are key factors affecting your performance.
Please tell us any
         metrics or other information you use to evaluate your success in these
areas and how
         you considered the need to disclose such information. Refer to Release
No. 33-10751.
Results of Operations, page 81

10.      To better illustrate the impact of pricing and volume changes on your
revenue, please
         revise to provide the total number of impressions delivered during the
reported periods,
         the average cost per impression or percentage changes in each. Also,
if material, disclose
         the reasons underlying changes in these factors during the reported
periods. Refer to
         section III.B.4 of Release No. 33-8350.
11.      Please quantify the impact of each material factor you discuss to
provide readers with
         better insight into the underlying reasons for the changes in your
results between reported
         periods. Where a material change is attributable to two or more
factors, including any
         offsetting factors, please provide quantification of the contribution
of each identified
         factor. Refer to Item 303(a)(3) of Regulation S-K and Section III.D of
SEC Release No.
Critical Accounting Policies, page 85

12.      To provide an indication of the level of judgment present in your
revenue policies, please
         revise to disclose the percentage of revenue generated from
usage-based contracts with no
         substantive minimum commitments.
13.      Please tell us why you have not included a discussion of the judgments
involved in
         determining the value of your units for calculating equity based
compensation. Refer to
         Section V of SEC Release No. 33-8350.
Management, page 104

14.      Please list the names and ages of the company   s directors and/or
director nominees, as
         well as the positions and offices held by such persons. Refer to Item
401 of Regulation S-
Principal Shareholders, page 119

15.      Please disclose the natural person or persons who exercise the voting
and/or dispositive
         powers with respect to the securities owned by Atlas Venture Fund
Consolidated Financial Statements
Note 2. Summary of significant accounting policies
(n)_Revenue Recognition, page F-11

16.      Please disclose how often you invoice customers and when payment is
typically due.
         Please also clarify whether you provide a right of refund to your
customers. Refer to ASC
 Joseph Pergola
Integral Ad Science Holding Corp.
March 11, 2021
Page 4
Note 12. Equity-based compensation, page F-24

17.      Please disclose the nature of the liquidity and exit event vesting
provisions for the Long-
         Term Incentive Payment (LTIP) and Return Target Option awards. Also,
describe for us
         the equity return multiple and unitholder return threshold criteria
that must be met in order
         for these awards to vest. Clarify how many of your options and LTIPs
would be vested if
         such provisions were met along with the related compensation cost that
would be
         recognized. Lastly, tell us your consideration to include any expense
incurred upon
         effectiveness of the IPO for these awards in your pro forma earnings
per share and balance
         sheet disclosures in the forepart of the filing.
18.      Please disclose the fair value of the underlying units (or a range of
values) for each period
         presented as this appears to be a significant assumption used in
determining the grant date
         fair value of your LTIP and option awards. Refer to ASC
19.      Please provide us with a breakdown of all equity-based compensation
awards granted
         during the year ended December 31, 2020 and to date in fiscal 2021,
and include the fair
         value of the underlying units at the date of such grants. To the
extent there were any
         significant fluctuations in the fair values from period-to-period,
describe for us the factors
         that contributed to these fluctuations, including any intervening
events within the
         company or changes in your valuation assumptions or methodology,
underlying units used
         to value such awards.

20.      Please file a consent for the third-party strategy consulting firm
that provided the 2021
         market study. Refer to Rule 436 of the Securities Act.
21.      Please file the executive employment agreements as well as all
material leases as exhibits
         to the registration statement. Refer to Item 601(b)(10) of Regulation

22.      Please supplementally provide us with copies of all written
communications, as defined in
         Rule 405 under the Securities Act, that you, or anyone authorized to
do so on your behalf,
         present to potential investors in reliance on Section 5(d) of the
Securities Act, whether or
         not they retain copies of the communication.
23.    You state that you have contracts with DSPs and proprietary platforms,
such as Google,
       Facebook, Amazon and The Trade Desk, and that termination of these
contracts would
       materially affect your revenue and results of operations. Please provide
the material terms
FirstName LastNameJoseph Pergola
       of your agreements with these companies, including the revenue-sharing
arrangements. To
Comapany    NameIntegral
       the extent material,Ad  Science
                            disclose theHolding Corp.
                                         percentage of total revenue
attributable to each of the
       agreements  for
March 11, 2021 Page 4  all periods presented.
FirstName LastName
 Joseph Pergola
Integral AdLastNameJoseph
            Science Holding Pergola
March      NameIntegral Ad Science Holding Corp.
       11, 2021
March5 11, 2021 Page 5
FirstName LastName
       You may contact Rebekah Lindsey, Staff Accountant, at (202) 551-3303 or
Kathleen Collins, Accounting Branch Chief, at (202) 551-3499 if you have
questions regarding
comments on the financial statements and related matters. Please contact
Alexandra Barone,
Staff Attorney, at (202) 551-8816 or Jan Woo, Legal Branch Chief, at (202)
551-3453 with any
other questions.


                                                          Division of
Corporation Finance
                                                          Office of Technology
cc:      Robert E. Goedert