They experience strain or stress, they become upset, and they sometimes engage in crime as a result. They may engage in crime to reduce or escape from the strain they are experiencing.
For example, they may engage in violence to end harassment from others, they may steal to reduce financial problems, or they may run away from home to escape abusive parents. They may also engage in crime to seek revenge against those who have wronged them. And they may engage in the crime of illicit drug use to make themselves feel better.
A recent version of strain theory is Robert Agnew's 1992 general strain theory. Agnew's theory draws heavily on previous versions of strain theory, particularly those of Robert Merton, Albert cohen, Richard Cloward and Lloyd Ohlin, David Greenberg, and Delbert Elliott and associates. Agnew, however, points to certain types of strain not considered in these previous versions and provides a fuller discussion of the conditions under which strain is most likely to lead to crime