Strain theory is a sociological and criminological concept that suggests that social structures within society may pressure individuals to commit crime. It was first developed in 1938 by Robert K. Merton and has since been expanded upon by other researchers such as Albert K. Cohen, Richard Cloward, Lloyd Ohlin, Neil Smelser, Robert Agnew, Steven Messner, Richard Rosenfeld, and Jie Zhang).

The theory posits that society puts pressure on individuals to achieve socially accepted goals, such as the "American Dream," even when they lack the means to do so. This pressure can lead to strain, which may prompt individuals to engage in criminal activities, such as selling drugs or becoming involved in prostitution, as a means to gain financial security).

There are different versions of strain theory, including general strain theory (GST) developed by Robert Agnew in 1992. GST addresses weaknesses in earlier strain theories and considers the role of emotion in strain-derived crime, as well as a broad range of possible sources of societal pressure that might cause a person to commit crime.

Strain can arise from various sources, such as the inability to achieve monetary success, lack of status, exposure to negative stimuli, and the inability to cope with negative emotions. These strains can lead to negative emotional responses, which individuals may attempt to cope with through criminal behavior.

In summary, strain theory in sociology and criminology suggests that societal pressures to achieve certain goals, combined with the inability to meet those goals, can lead individuals to engage in criminal activities as a means of coping with the resulting strain.