Best team of PhS supervisors

#68: PhD Support: Pick the perfect co-supervisor

Are you aware of how much a good co-supervisor can influence your PhD process? Did you know that many PhD students can add co-supervisors throughout their PhD? Not sure who you should pick? Here, we outline the process for finding the perfect co-supervisor, and provide our helpful worksheet ‘Select the perfect PhD co-supervisor’ to move you straight into selecting your prime candidates.

It’s pretty clear to every PhD student what function their main PhD supervisor or advisors plays, and that this person has an important influence on their PhD projects. But in addition to that, PhD candidates have co-supervisors, and what their roles are is often less obvious. In many PhD programmes, PhD candidates can suggest co-supervisors that they find beneficial to their projects. But not everyone is aware that this opportunity exists, and that it is a great chance to get highly relevant experts on board who can really help to elevate a PhD project to another level. Not selecting appropriate co-supervisors for your PhD project is a missed chance that may never come again. 

Many aspects of finding great supervisors do apply to the main supervisor and the co-supervisor alike, see (Killeya 2008, Academic Positions Career Advice 2018, Francis 2019) but co-supervisors can often be appointed while you already work on your PhD research. That’s a big plus, because you do have to have all of them on board when you are starting out!

With this blog-post, we want to clarify the position of co-supervisors, and draw your attention to why having good co-supervisors is important for your PhD success. On top of that, we give you practical advice on how to come up with a list of prime-candidates for yourself. Co-supervisors will support you and be close allies throughout your PhD process. Grab our free worksheet ‘Select the perfect PhD co-supervisor’ for all the details.

Who are we talking about? 

Besides the main supervisor or advisor, most PhD students have further scientists who give additional supervision. The persons besides your main supervisor can be called co-supervisors, co-advisors, second supervisors/advisors, or mentors. So don’t get confused here – it’s all the same principle no matter what they are called in your graduate programme. We call them ‘co-supervisors’ in this post. 

What do co-supervisors do?

Your main supervisor has the overall responsibility to support and guide you throughout your PhD process from start to finish. If you want an overview regarding their roles & responsibilities, check our blog post no. #10: Good PhD-supervision: What you can expect. 

The role of a co-supervisor has to be seen in respect to the main supervisor. In principle, a co-supervisor can have the following functions: 

• Double-up: As a double-up for the main supervisor. This is often the case if you have one main supervisor and one co-supervisor. The co-supervisor gives you additional supervision, but the main responsibility falls on your main supervisor. No specific roles are defined for the co-supervisor in this case. Think of president and vice-president, or chancellor and vice chancellor. 

• Team-member: While the main-supervisor is the team-leader and has overall responsibility, the co-supervisors add additional expertise. Their function is often specified (e.g. they help you with a particular aspect of your project). Together they have complementary expertise. Think of them as a team of supervisors who provide you with support. 

• Mentor: The co-supervisor as mentor often occurs in combination with point 2 above. Here, one co-supervisor has a special function as mentor and career advisor. The mentoring role emphasises the non-scientific guidance that this person is giving you. 

How many co-supervisors can one have?

The number of co-supervisors you should or may have varies. Having 1-3 co-supervisors is common, but it’s often possible to have more than that if it makes sense in the context of your PhD project. All supervisors together form your supervisory committee (also called PhD advisory committee, thesis advisory committee, or supervisory board). 

Depending on your PhD programme and regulations, co-supervisors can be added (and rotated off again) to your committee during various phases of your PhD. So you do not necessarily have to have all of them on board right at the start. Nor do you always have the same number of co-supervisors throughout your entire PhD. Herein is a great chance for all of you who think they would benefit from having another supervisor on board – go ahead and see if they can be added to your supervisory committee. 

Advantages of good co-supervisors

The advantages of having good co-supervisors can’t be emphasised enough – here are the most important points:

• More experts, better quality. Having additional experts for particular aspects of your PhD does greatly enhance the quality of your PhD project. You can learn specialty methods or techniques quicker, and trouble-shooting is easier. You’re exposed to various schools of thought. 

• Multiplicity of personalities. Supervision is not just about the science, but involves a great deal of personal contact. You’ll benefit from having multiple personalities available, so there’s a better balance overall. If you’re fed up and tired of one, there’s still others you can rely on.

• Checks and balances. Your project (and you) won’t be dominated by just one influencer, and you reduce the risk of being dependent on a single person. There’s a better chance that formal procedures of graduate schools and universities will be followed to your benefit. In a case of conflict with the main supervisor or one co-supervisor, you have others to talk to.

• Future network. Co-supervisors are great future collaborators and academic contacts. They know you and your work in detail and can help you form an international profile early on. 

• Ease burden on one supervisor. You can have more and better supervision overall, without overburdening one person.

Who appoints co-supervisors?

The main supervisor is often fixed from the start because you applied for a PhD position with this person or you selected them as a supervisor for your project. Co-supervisors, in contrast, are often appointed during the initial phase of your PhD. At most universities or graduate programmes, you’ll discuss potential co-supervisors with your main supervisor, and register the ones you agree upon. And here’s the problem – at the start, PhD candidates are not always aware of the importance of this step, and that they often have the right to suggest candidates. All too often, main supervisors, due to time constraints or lack of better ideas, tend to invite their best academic buddies or the colleagues they alway work with. This might be convenient and trouble-free for them, but is not necessarily the best bet for you. If your guidelines allow for it, make sure to suggest potential co-supervisors.  

You’ve got to realise this: A non-supportive co-supervisor is of little to no help with your PhD research. A good and supportive one will amp up the quality of your research and the overall success of your PhD project. Which option do you want?

Get our free worksheet ‘Select the perfect PhD co-supervisor’ so you know how to arrive at a list of great candidates. Discuss your perfect candidates with your main supervisor, and make explicit who you want and why. Then you can approach your favourite candidates and ask if they would be available (and mention that you discussed the matter with your main supervisor), or your main supervisor may contact them on your behalf. Once you have their agreement, they will be formally registered as co-supervisors with your graduate school or university. 

Who can be a co-supervisor? 

A scientist in your research field with the appropriate expertise is an ideal co-supervisor. Check the regulations of your university or graduate programme. While there are universities where main-supervisors of PhD candidates have to be full-professors, the requirements for co-supervisors are often more flexible. In principle you can appoint any researcher or scientist in your field as co-supervisor, occasionally also a postdoc or industry expert. Co-supervisors can come from outside your own department or faculty, and international expertise from abroad is often welcome (details are specified in your PhD regulations). This can greatly widen the pool of candidates for you and is a fantastic chance to get the very best support for your project.

How to select the perfect co-supervisor?

It is not all too difficult, if you widen the pool of people you can ask and do a brief strategic search online. In our Worksheet: Select the perfect PhD co-supervisor, we have included step-by-step guidelines that give you all the important details to consider. To just give you a teaser: You should get a head-start by identifying the exact areas of specialism you’d need for your PhD project. In the second step, you brainstorm for researchers from nearby (your work-group, department, institute) as well as further away who might be great to have. But you’ll also consider personalities, career-level, their track-record, and much more! Curious? Download our free worksheet “Select the perfect PhD co-supervisor”.


Having a supportive group of supervisors can be a huge benefit to your PhD. Don’t just settle for what your main supervisor suggests, but do the legwork yourself and make sure you have people at your side that help to elevate your research and are great to work with. 

Keep your eyes and ears open for add-ons to your supervisory team as you proceed with your PhD. If you get to know more academics that would be an asset to your advisory board, don’t hesitate to pave the way and ask if they would be willing to come on board as co-supervisors. 


Worksheet “Select the perfect PhD co-supervisor”

Blog post no. #10: Good PhD-supervision: What you can expect. 

Killeya, Matthew 2008: The PhD journey: How to choose a good supervisor. New Scientist. 

Francis, Chantelle 2019: 6 Things to look for in a PhD supervisor. 

Academic Positions Career Advice 2018: How to Choose Your PhD Supervisor. 

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