\( \frac { 1 } { 1.2 } + \frac { 1 } { 2.3 } + \frac { 1 } { 3.4 } + \ldots + \frac { 1 } { 2011.2012 } \)

To evaluate the sum \( S = \frac{1}{1.2} + \frac{1}{2.3} + \frac{1}{3.4} + \ldots + \frac{1}{2011.2012} \), we start by recognizing the pattern in the general term: \[ \frac{1}{n(n+1)} = \frac{1}{n} - \frac{1}{n+1} \] This transformation allows us to rewrite the sum: \[ S = \left( \frac{1}{1} - \frac{1}{2} \right) + \left( \frac{1}{2} - \frac{1}{3} \right) + \left( \frac{1}{3} - \frac{1}{4} \right) + \cdots + \left( \frac{1}{2011} - \frac{1}{2012} \right) \] By observing the structure of the sum, we notice that it is a telescoping series, where many terms cancel out: \[ S = 1 - \frac{1}{2012} \] After cancellation, we are left with: \[ S = \frac{2012 - 1}{2012} = \frac{2011}{2012} \] Thus, the final result is: \[ \boxed{\frac{2011}{2012}} \]