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                             July 6, 2023

       Joseph Campanelli
       President, Chief Executive Officer
       NB Bancorp, Inc.
       1063 Great Plain Avenue
       Needham, Massachusetts 02492

                                                        Re: NB Bancorp, Inc.
                                                            Registration
Statement on Form S-1
                                                            Filed June 9, 2023
                                                            File No. 333-272567

       Dear Joseph Campanelli:

              We have reviewed your 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 amending your registration
statement and providing the
       requested information. 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
       response.

              After reviewing any amendment to your registration statement and
the information you
       provide in response to these comments, we may have additional comments.

       Form S-1 filed June 9, 2023

       Risk Factors
       Our portfolio of commercial real estate loans and commercial and
industrial loans...involve
       credit risks..., page 17

   1.                                                   We note your statement
regarding your lending activities that "[s]uch loans typically
                                                        involve larger loan
balances to single borrowers or groups of related borrowers compared
                                                        to one- to four-family
residential mortgage loans. In addition, the repayment of these
                                                        types of loans depends
on the successful management and operation of the borrower   s
                                                        businesses or
properties." Revise this risk factor to state your current loan to one
                                                        borrower limit, as well
as the amounts of your four largest customer relationships as of a
                                                        recent date.
 Joseph Campanelli
FirstName   LastNameJoseph Campanelli
NB Bancorp,    Inc.
Comapany
July 6, 2023NameNB Bancorp, Inc.
July 6,2 2023 Page 2
Page
FirstName LastName
The geographic concentration of our loan portfolio and lending activities, page
19

2.       Revise this risk factor to discuss, as appropriate, the factors that
impact the current Greater
         Boston commercial real estate market. For instance, discuss any
changes in occupancy for
         office, industrial or retail real estate.
Uncertainty about the future of the London Interbank Offered Rate, or "LIBOR,"
may adversely
affect our business, page 22

3.       Please disclose to what extent your existing loans, deposits, and
other financial
         instruments, including your existing swap contracts, have interest
rates that are set by
         reference to LIBOR. For each significant asset or liability that is
currently priced based
         on reference to LIBOR, clarify whether you have evaluated whether the
contractual
         language will permit conversion to a new reference rate.
The fair value of our investment securities can fluctuate, page 26

4.       Revise this risk factor to disclose recent experience with unrealized
gains or losses on
         your securities portfolio.
Risks Related to Our Funding, page 27

5.       Revise this section to discuss the impact on your ability to utilize
both FHLB borrowings
         and/or brokered deposits in the event that your capital position
declined below "well
         capitalized" or if your net tangible equity were to decline.
Management of Market Risk, page 75

6.       We note your statement that the "Asset Liability Committee is
responsible for managing
         market risk." Please revise this section, or another appropriate
section, to discuss the
         membership of the Asset Liability Committee. Disclose whether the
committee reports to
         the Board or any of the four standing committees of the Board.
Competition, page 84

7.       You note that since 2017 you have expanded, and intend to continue to
expand, into
         commercial and industrial lending. Please disclose whether you compete
with particular
         larger and/or more well-established competitors in this segment of
your lending
         operations. If there are dominant competitors in a key market segment,
revise this section
         to identify those competitors. Discuss the extent to which the ability
to compete in this
         area is dependent on existing relationships, and how this might impact
your business
         strategy to focus in the commercial and industrial lending areas. Make
appropriate
         changes to your management's discussion and/or risk factors based on
your response.
 Joseph Campanelli
FirstName   LastNameJoseph Campanelli
NB Bancorp,    Inc.
Comapany
July 6, 2023NameNB Bancorp, Inc.
July 6,3 2023 Page 3
Page
FirstName LastName
Business of Needham Bank
Sources of Funds, page 103

8.       Revise this section to clarify whether NB Bancorp will continue to
offer full insurance
         coverage for its deposits from the DIF after the conversion of Needham
Bank from a
         cooperative bank charter.
9.       Revise your discussion of your deposits to note whether your
depositors have any
         significant concentrations among your depositors, particularly for
your larger deposit
         accounts. For example, disclose any deposits focused in the tech
industry, venture capital
         funds or portfolio companies, or out of market firms.
Management of NB Bancorp
The Business Background of Our Directors and Executive Officers, page 121

10.      Please revise the business background information for Mr. Orfanello to
confirm that his
         position as partner at One Rock Capital began more than five years
ago. Alternatively,
         please revise to provide a complete description of his business
experience in the last five
         years. Refer to Item 401(e)(1) of Regulation S-K.
Consolidated Financial Statements of NB Financial, MHC and Subsidiary
Note 5     Mortgage Banking     Loan Sales and Servicing, page F-68

11.      We note your disclosure on page F-68 that the carrying value of
mortgage servicing rights
         exceeded their fair value at December 31, 2022, and that no adjustment
for impairment
         was recognized. Please tell us and revise to clarify if the    balance
at the end of year    in
         the table on page F-68 is the carrying value or fair value of your
mortgage servicing
         rights. In addition, please tell us how you determined that an
impairment was not
         necessary given that the carrying value exceeded fair value. Please
refer to ASC 860-50-
         35-9.
Exhibits

12.      Both exhibit 10.1 and 10.2, the employment agreements between Needham
Bank and
         Messrs. Campanelli and Rinaldi respectively, were effective through
January1, 2023. On
         page 126, you indicate that Needham Bank has entered into new
employment agreements
         that expire in 2026 and 2025 respectively. Please include the new
agreements as exhibits
         in your next amendment.
        We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence of
action by the staff.

       Refer to Rules 460 and 461 regarding requests for acceleration. Please
allow adequate
time for us to review any amendment prior to the requested effective date of
the registration
statement.
 Joseph Campanelli
NB Bancorp, Inc.
July 6, 2023
Page 4

        You may contact Katharine Garrett at 202-551-2332 or William Schroeder
at 202-551-
3294 if you have questions regarding comments on the financial statements and
related
matters. Please contact Aisha Adegbuyi at 202-551-8754 or Christian Windsor at
202-551-
3419 with any other questions.



                                                         Sincerely,
FirstName LastNameJoseph Campanelli
                                                         Division of
Corporation Finance
Comapany NameNB Bancorp, Inc.
                                                         Office of Finance
July 6, 2023 Page 4
cc:       Steven Lanter
FirstName LastName