X0303 4 2011-04-15 0 0001488139 Ameresco, Inc. AMRC 0001496421 Derrington Keith A C/O AMERESCO, INC. 111 SPEEN STREET , SUITE 410 FRAMINGHAM MA 01701 0 1 0 0 Executive Vice President Class A Common Stock 2011-04-15 2011-04-15 4 M 0 8000 2.75 A 8000 D Class A Common Stock 2011-04-15 2011-04-15 4 S 0 8000 15.00 D 0 D Class A Common Stock 2011-04-18 2011-04-18 4 M 0 8000 2.75 A 8000 D Class A Common Stock 2011-04-18 2011-04-18 4 S 0 8000 15.722 D 0 D Stock Option (right to purchase) 2.75 2011-04-15 2011-04-15 4 M 0 8000 0.00 D 2014-06-25 Class A Common Stock 8000 67000 D Stock Option (right to purchase) 2.75 2011-04-18 2011-04-18 4 M 0 8000 0.00 D 2014-06-25 Class A Common Stock 8000 59000 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 8, 2011. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.52 to $15.90, inclusive. The reporting person undertakes to provide to Ameresco, Inc., any security holder of Ameresco, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in footnote (2) to this Form 4. Of the shares subject to the option, 20% vested on June 25, 2005, and the remainder vested in 16 equal quarterly installments thereafter. David J. Corrsin, Attorney-in-fact 2011-04-19