No;  wave interference takes place whenever two waves of any frequency, same, nearly the same or widely different interact. An air molecule next to your ear, for example, can only respond to the ***sum*** of all the different sound waves reaching it at any moment. 

The results are ***simpler*** when the two waves are closely related, or some simple multiple of each other.  One common effect caused by the interference closely related frequencies is the phenomenon of ***beats***.

This video, http://video.mit.edu/watch/tuning-forks-resonance-a-beat-frequency-11447/, . at about the $1:30$  mark, shows the result of adding two sound waves of ***almost*** the same frequency.  The rider on the tine of one of the two tuning forks detunes it slightly.  The two resulting waves can interferes constructively, then destructively, and then back again.

I've done this demonstration with a group of students around the apparatus.  By asking the students to individually raise their hand when **they** heard the loudest sound, it becomes clear that the moment when the two waves arrive ***in step*** for any student depends on their position around the apparatus.

Edit:

In the general case, with no assumptions about the frequency, shape, phase or amplitude of the two waves, the Superposition Principle applies:  
http://en.wikipedia.org/wiki/Superposition_principle

 Consider the first of the waves.  What would the medium be doing at that instant, ***if this were the only wave acting***?.  Say we're talking water waves, and the answer is that the water would be 20 cm above its normal position. 

 Do the same for all the other waves present, keeping track of each answer, and noting in each case whether the water is above or below its undisturbed position.

Finally, add up all the individual displacements.  The result is the position of the water at that instant.

Move forward a short period of time and repeat.  The sequence of displacements versus time give nature of the resulting wave.