Albert Bandura is a contemporary modern theorist who is notable for studies in "social learning theory" or what is known as Social Cognitive Theory. He bases his studies and research out of Stanford University.
Social learning theory and criminology
Social learning theory is a valuable tool in understanding criminal behavior and is therefore studied as a criminology discipline. Social learning theory helps criminologists understand why people "commit violent acts and crime." 
Through the study of social learning theory, sociologists and criminologists can help to reduce criminal behavior and crime.
Social learning theory and aggression
Albert Bandura argued that aggressiveness is learned through life experiences; and that "people are not born with the ability to behave violently." 
Personal life experiences included "observing others acting aggressively to achieve some goal or watching people being rewarded for violent acts on television or in the movies." 
Both children and adults model behavior of the people they live with and live around in their communities. By modeling behavior, people watch and observe the behavior of parents, teachers, siblings, and their peers.
However, negatively modeled behavior such as extreme violence seen by children in their families is the type of behavior that helps to develop a violently prone personality. Violent behaviors observed by children will persist into later life in their social relationships.
There may be aggressive responses by both children and adults to "direct, pain-producing, physical assaults; or verbal taunts and insults."
Three sources of aggressive behavior modeling are:
1) Family interactions
Aggressive children come from aggressive families. 
2) Environmental experience
The communities and families children live in do not exhibit conventional behavior; violence might occur daily. 
3) Mass media
Children and adults observe graphical depictions of violence in the movies and on TV programs. 
Albert Bandura wrote notable books about social learning theory and aggression: Adolescent Aggression (1959); Aggression: A Social LearningAnalysis (1973); and A Social Learning Analysis (1977).
Social learning as observational learning
"Both classical and operant conditioning can occur indirectly when one person observes another's conditioning."  In other words, a person can learn through watching or observing how other persons solve life problems, and then imitate what they see.
When children or adults model behavior they are watching or observing the model or the parent, teacher, or peer that they are closely alligned with. The person the child or adult models is called the "model."
One model may be more influencial than another model depending on the amount of respect the child or adult has for that model. Both children and adults imitate the behavior of people they respect more than people they don't respect.
People will also imitate those people or models they consider attractive or powerful such as a famous movie star or rock star. People will also be "more likely to imitate a model if the model experiences positive outcomes."
Self-efficacy refers to "one's belief about one's ability to perform behaviors that should lead to expected outcomes." 
People can have high and low self-efficacy; and will execute responses that will earn reinforcements. Challenges that people attempt are greatly influenced by their direct perception of their own self-efficacy.
In conclusion, Albert Bandura's "social learning theory" gave greater insight into violence and aggression and how people learn aggressive behaviors as young children. He also shows how both children and adults learn behaviors by watching or observing other people in their environments. Behaviors learned can be either negative or positive according to the models they observe.
5) Siegel, Larry J., Criminology, Wadsworth, Belmont, CA, USA, 2005
6) Weiten, Wayne, Psychology, 6th ed., Wadsworth, 2005.