Certainly there are different ways that mission agencies work. It is hard to encapsulate everything they do and what their purpose is, but here are some general things that can be said about the role of a missions agency. Each agency will have greater or lesser emphasis on these points; but, generally, you will find each of these in the structure of a mission board.
Types of Missions Agencies
Before we discuss the role of a mission agency, let’s look at two general types of mission groups. These represent the two ends of the spectrum for mission agency involvement in the life of the missionary .
There are mission agencies that play the role of employer for the missionary. The individual missionaries are hired as workers and are told where to work and how to conduct their ministry. That may sound like it takes the role of the Holy Spirit’s leading out of the decision-making process for the missionary, but these types of agencies work well in certain types of ministries. Their value is particularly seen in situations where a large team is working together to accomplish a task. These are usually infrastructure type ministries as opposed to local church planting. Some examples would be hospital ministry, large Bible colleges, and other types of educational projects.
On the other extreme of mission board involvement is what we call a clearinghouse. These are mission agencies that simply process money for the missionary. They provide the tax-deductible authority for a missionary to receive money. They issue receipts to the donors and help take care of the legality of the missionary operating as a non-profit entity. Clearinghouses do not get involved in providing any type of ministry accountability or guidance. In these situations it is assumed that the church and pastor who have sent out the missionary will provide the biblical accountability for the missionaries’ ministry activities.
The vast majority of missions agencies work in between these two opposite ends of the agency/missionary relationship.
In both of the above examples, and every other type of board, there are two main types of accountability that are provided by the missions agency—ministerial and financial accountability. When I started out in my ministry as a foreign missionary, I got some great advice concerning accountability which I share here as examples of the role of the mission agency.
A friend advised me that I could work out of my sending church without a mission board, but that I would not have the ministry accountability that I probably needed. My pastor would not be checking up on me every week to see how I was doing in my work. My friend was absolutely right. Though I have a great relationship with my pastor, he has his own ministry which keeps him from providing regular accountability on my ministry and work goals.
Most mission agencies do not tell the missionary how he should conduct his work, but there is accountability to know that the missionary is actually doing the ministry for which he has raised his support. This is done by way of the agency tracking the ministry reports of the missionary. Many mission boards have directors and representatives who can visit the missionary on their field. This is not to check on the missionary like a manager over the ministry, but to provide spiritual encouragement  and offer suggestions that usually come from greater experience in the ministry.
The second bit of advice I got came from two different pastors. When they sent their monthly financial support to me they wanted to know that the money was being handled in a fiscally responsible way. They wanted a report from the mission board that their money was received and distributed to me properly. Both these pastors were personal friends and had no doubt that I would use the money properly. Their concern came from sending their support checks to my home church—which they had no relationship with—and not having any guarantee that their money was being distributed to my ministry.
Not every pastor will have first-hand knowledge of every mission board that they send money through, but the nature of a mission agency is such that it will not function very long if the money is not handled properly. This gives pastors and individual supporters a bit more assurance that the money is handled in a proper way.
Most missionaries go to the field needing guidance on the financial requirements for the field in which they will minister. A missionary working in an urban ministry in Japan or Hong Kong will need considerably more monthly support than a missionary working in tribal ministry in South America. How much more he needs, and for what purposes, is exactly the types of questions a mission agency can help answer. Generally the fear is not that a missionary will raise more money than he needs and that he simply lives a life of luxury in an exotic location. The real issue is that missionaries are so eager to get to the field and do the work that they generally are willing to go woefully under-supported. This results in missionaries struggling to survive. It keeps them from effectively doing their ministry and puts a tremendous strain on their family. Sadly, many missionaries leave the field because of financial issues. A missions agency can help guide the missionaries in avoiding such situations.
Another practical way in which the agency helps the missionary is simply fulfilling the legal requirements for reporting income and handling taxes. Someone needs to keep accurate records of donations and issue receipts to the donors. By using a mission agency, the missionary is free to focus more on ministry and less on the obligatory financial accounting that someone else can handle for him.
The third general area in which a mission agency helps the missionary is in ministry guidance. This is done through passing along experience gained by others so that the missionary does not need to flounder through the basics of getting started.
Most missionaries will have a proper degree from an institute of higher learning for the ministry that they will be involved with. However, nothing quite provides the specific education that living on the field and doing the ministry can provide. A mission board can provide the training the missionary needs, or can recommend resources for the missionary that will help them in their type of ministry or country. A missionary sent out from his home church without the aid of a mission board will lack this vast wealth of knowledge that an established mission agency can provide.
On the secular side of ministry guidance is the legal aspect of mission work. Both at home and on the foreign field there is a role that the missions agency plays for the missionary. I’ve already mentioned the financial aspect. The agency can provide the income reporting for the missionary that the home government requires. But there are other legal matters that the agency can help resolve for the missionary.
It depends on the country where the missionary is going, but many countries don’t want a person requesting a visa to do ministry in their country without some type of parent organization over the endeavor. A legally recognized agency can facilitate a missionary getting into a country to do their ministry. Governments want as much assurance as they can get that the person requesting entrance to their borders is not a charlatan who will fleece the people and leave them in a worse condition than when they came. Again, not all countries require this, but using a mission organization to provide the legal authority for the missionary certainly helps.
There are many more practical things that could be said about a missions agency, but these are the main roles that an organization plays in the life of the missionary. Not all mission agencies are the same. If you are considering becoming a missionary, you should talk with your pastor and get recommendations from him on what mission agency you should talk with. Most pastors will have a definite opinion on what makes a good missionary group and will make appropriate suggestions for you.