Social and Cultural Groups
In looking at social psychology we could start with the broader view and then move to the more narrow one.  Looking at the social in broad terms we see cultural and linguistic groups that define the natural social groups in which we live.  

Cultural psychology involves the understanding of human psychosocial life through the following Cultural principles:
Mediation through artifacts - Culture involves the creation and use of tools, artifacts and icons that are given practical and symbolic meaning through ritualized collective action.

Historical Development - Cultures and their phenomena are situated in a historical time and place.  They undergo transformation and change in meaning and form.

Practical Activity - To understand a culture one must understand it as an everyday phenomenon, not as an object to  be dissected in a laboratory.  It involves the everyday practical activities of people in various social relationships, each imbued with symbolic meaning, political power, right, duties and responsibilities. (Cole, 1996) 

Living through culture and history -> identity as a lived process...

Erik Erikson (1965)  wrote on psychosocial identity where he
views identity as inherently a cultural phenomenon.

Being grounded in one's class, nation, linguistic, ideological, religious, philosophical world views and traditions identity emerges like a flower from soil, sunlight, water, and air.  Our culture is our Self.

Research on the meaning of being Canadian and Ethnic is as follows: Tonks (1998): Study on the top categories / responses to:  What does it mean to be Canadian?

When people move from one country or society or even community, to another, they usually undergo some type of acculturation, or adjustment.

Acculturation involves the collection of processes surrounding the adjustments required when people from two or more cultures come together for continuous first hand contact. Acculturation Activity

The coming together of people from different cultures can be a very positive experience where new traditions are formed in the bonds between the older cultural practices. Other times the coming together of people from different cultures is not as positive . . .

Additionally the Self across Cultures? has been shown to vary considerably.

Prejudice is the general phenomenon of pre-judging and can be explained through a number of theories.

Social influence and individual group behaviour has been examined in American social Psychology where a number of interesting phenomena have been observed.  In knowing about these phenomena, change has happened in our society.  This marks one area of the application of social psychology to the social world around us.