The range of jobs is huge! Here they are broken into four categories:

1. There are low-skilled jobs that don't require specialized education, but where you also won't get to work directly with animals, such as:
   • Menial jobs, such as cleaning up after animals or preparing their living spaces
     
   • Low-skilled administrative jobs, such as answering the phone
    
   
2. There are administrative and program jobs that do require at least some experience and training that are in support of the organization, but where you may also not work directly with animals, such as:
   • marketing
     
   • public relations
     
   • interpretive naturalist
     
   • program director
     
   • educator
     
    
   
3. There are jobs that allow you to work with animals and don't require a four-year degree (but they require a certificate or two-year degree), such as:
   • pet sitter/dog walker
     
   • dog trainer
     
   • veterinary technician
     
   • wildlife rehabilitator
    
   
4. There are jobs where you work some of the time or all of the time with animals and do require a university education (often an advanced degree), such as:
   • biologist
     
   • forest ranger / park ranger
     
   • veterinarian (small animal vets, large animal vets, exotic animal vets for zoos, research veterinarians, etc.)
     
   • therapy for humans that uses animals
     
   • animal psychology
     
   • habitat specialist
     
   • conservation officer
     

• animal shelters (run by the SPCA, local Humane Society, a local city or county government, or a local non-profit)
  
• zoos
  
• veterinary offices
  
• universities
  
• secondary schools
  
• farms
  
• nature centers
  
• parks
  
• wildlife rehabilitation centers
  
• human rehabilitation centers
  
• prisons (where there are a growing number of programs where prisoners care for and train animals)
  

• ecology
  
• biology (including specialist areas, such as marine biology)
  
• veterinary medicine
  
• zoology
  
• shelter management
  
• animal psychology
  
• environmental management
  
• environmental science
  
• conservation
  
• natural resources management
  
• fisheries and wildlife sciences
  

Another helpful resource: Careers for creature lovers, a guide to animal-related careers from the U.S. Bureau of Labor Statistics.

 
Also see

How to Get a Job with the United Nations or Other International Humanitarian or Development Organization

Volunteering In Pursuit of a Medical, Veterinary or Social Work degree / career

Details on volunteering abroad (volunteering internationally).

Ideas for Funding Your Volunteering Abroad Trip.

For Teens: Finding Community Service and Volunteering

How to Find Volunteering Opportunities, a resource for adults who want to volunteer

Creating or Holding a Successful Community Event or Fund Raising Event.

Fund Raising For a Cause or Organization

Detailed advice for volunteer groups / group volunteering.

Volunteering with Seniors.

How to Make a Difference Internationally/Globally/in Another Country Without Going Abroad

Ideas for Leadership Volunteering Activities
These are more than just do-it-yourself volunteering - these are ideas to create or lead a sustainable, lasting benefit to a community, recruiting others to help and to have a leadership role as a volunteer. These can also be activities for the Girl Scouts Gold Award, the Duke of Edinburgh's Award (U.K.), a mitzvah project, or even scholarship consideration.

Volunteering To Help After Major Disasters.

Donating Things Instead of Cash or Time (In-Kind Contributions)

Details on how to quickly fill a community service obligation from a court or school.

Helping People Address Their Problems with Plastic
How to mobilize a community to clean up plastic bottles, plastic bags and other plastic waste from their environment, and how to reduce their use of such items in the future