If you performed the duties listed for NOC 4152 for at least one year then you are eligible to apply. Check your job duties to what is in the noc description and if the majority match then you are good to go. Here's a link to the duties (also see Mandie has kindly put a link to job duties in her siggy) http://www.canadavisa.com/social-workers-4152.html
Social workers help individuals, couples, families, groups, communities and organizations develop the skills and resources they need to enhance social functioning and provide counselling, therapy and referral to other supportive social services. Social workers also respond to other social needs and issues such as unemployment, racism and poverty. They are employed by hospitals, school boards, social service agencies, child welfare organizations, correctional facilities, community agencies, employee assistance programs and Aboriginal band councils, or they may work in private practice.
(Description from Human Resources and Skills Development Canada's National Occupation Classification, used by Canadian immigration officers, to assess an applicant's work experience.)
Social workers perform some or all of the following duties:
Interview clients individually, in families, or in groups, to assess their situation and problems and determine the types of services required
Provide counsel and therapy to assist clients in developing skills to deal with and resolve their social and personal problems
Plan programs of assistance for clients including referral to agencies that provide financial assistance, legal aid, housing, medical treatment and other services
Investigate cases of child abuse or neglect and take authorized protective action when necessary
Serve as members on interdisciplinary teams of professionals working with client groups
Act as advocates for client groups in the community, lobby for solutions to problems directly affecting client groups and develop prevention and intervention programs to meet community needs
Develop or advise on social policy legislation, conduct social research and assist in community development
Provide mediation services and psychosocial assessments
Evaluate the effectiveness of counselling and social programs
May provide public education and consultation to professionals or groups regarding counselling services, issues and methods
May supervise other social workers.
Social workers may specialize in fields of practice such as child welfare, family services, corrections, gerontology or addictions.