EXHIBIT 11

UNITIL CORPORATION AND SUBSIDIARY COMPANIES

COMPUTATION OF EARNINGS PER WEIGHTED AVERAGE COMMON SHARE OUTSTANDING

(Millions
except common shares and per share data)

(UNAUDITED)



|                                                                       |  |                                 |        |                                |      |   |       |  |      |       |  |   |      
|---------------------------------------------------------------------- |  | ------------------------------- | ------ | ------------------------------ | ---- | - | ----- |  | ---- | ----- |  | - | -----
|                                                                       |  | Three Months EndedSeptember 30, |        | Nine Months EndedSeptember 30,
|                                                                       |  | 2009                            |        |                                | 2008 |   | 2009  |  | 2008
|Net Income (Loss)                                                      |  | $                               | (0.6   | )                              |      | $ | 1.5   |  | $    | 8.8   |  | $ | 6.5  
|Less: Dividend Requirements on Preferred Stock                         |  |                                 |       |                                |      |   |      |  |      | 0.1   |  |   | 0.1  
|                                                                       |  |                                 |        |                                |      |   |       |  |      |       |  |   |      
|                                                                       |  |                                 |        |                               
|Net Income Applicable to Common Stock                                  |  | $                               | (0.6   | )                              |      | $ | 1.5   |  | $    | 8.7   |  | $ | 6.4  
|                                                                       |  |                                 |        |                                |      |   |       |  |      |       |  |   |      
|                                                                       |  |                                 |        |                               
|Weighted Average Number of Common Shares Outstanding  Basic (000s)   |  |                                 | 10,767 |                                |      |   | 5,745 |  |      | 9,267 |  |   | 5,733
|                                                                       |  |                                 |        |                               
|Dilutive Effect of Stock Options and Restricted Stock (000s)          |  |                                 |       |                                |      |   | 3     |  |      |      |  |   | 5    
|                                                                       |  |                                 |        |                               
|Weighted Average Number of Common Shares Outstanding  Diluted (000s) |  |                                 | 10,767 |                                |      |   | 5,748 |  |      | 9,267 |  |   | 5,738
|                                                                       |  |                                 |        |                               
|Earnings Per Share  Basic                                             |  |                                 | ($0.06 | )                              |      | $ | 0.27  |  | $    | 0.94  |  | $ | 1.12 
|                                                                       |  |                                 |        |                               
|Earnings Per Share  Diluted                                           |  |                                 | ($0.06 | )                              |      | $ | 0.27  |  | $    | 0.94  |  | $ | 1.12