If the company is focusing on one or several industries, it is more likely to have more knowledge and experience in it, and so they can offer a better quality service.
It is important that the company has established themselves in an industry and have made contacts and relationships, and have a good reputation in the industry.
An experienced company with specific knowledge in the field will know what qualities of the workers are necessary for a certain field so that the needs of your company would be met.
Staffing industry is rather hard to understand quickly, so the longer the company is in the industry, the better. Also, word-of-mouth is very important in this industry, so ask your partners or look for recommendations on the Internet in order to make the best choice.
All companies must know that first impression makes a huge difference, and staffing agencies are not exclusion. Look at how polite they are, what kind of emotion they carry throughout the conversation. If you have a chance to meet them, look at their professionalism as well as humanism. Try to see what the atmosphere inside the team is. If you manage to read between the lines, you will be able to determine how they treat their clients and workers, and what the overall satisfaction within the company is.
What kind of worker exactly do you need? Will you need seasonal employment, or a longer term employee? What are the specifics of your company? Take a look at how the company is dealing with the details, because it is a good measure of their professionalism.
Ask for references; look up the company on the Internet. Temporary employment agencies work directly with people, so they must be good with people, and if they are not, people will most likely complain. Thus, do some research to find out what is the experience of other companies with that specific staffing agency.
Read through the contract and check if it does not have any unclear areas. If there is any suspicion, ask the company about it, and if they are not able to answer it clearly, they might be either not very good at dealing with people, or trying to hide something. In any of these cases, you are likely to find a more suitable partner somewhere else.
These are probably the most important questions to answer before choosing a staffing agency. If you are in doubt of how to determine the credibility of your partner, use this model to make your task easier.
Also, I invite you to share how you determine the reputability and credibility of your partner temporary staffing agencies. What criteria do you use?