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At Caltech, we have a unique organizational structure. An "option" is our word for "academic program". At Caltech, most options are housed within one of Caltech's six academic divisions. ESE has faculty members from several divisions, including the Division of Chemistry and Chemical Engineering, the Division of Geological and Planetary Sciences, and the Division of Engineering and Applied Science.

When you apply to Caltech you apply to an option, not a division. Your option will determine what classes you take, the requirements for completing your Masters and then PhD, and also the structure of your qualification exam. At Caltech, our small size allows us to be flexible in terms of course requirements and research projects, which often span multiple options. Some faculty members have dual appointments in different options and divisions, and you are allowed to work with faculty outside of your option. We strongly encourage applicants to contact potential advisers to seek advice on the option to which they apply.

There are approximately 3-8 incoming students per year, for a total of about 30 graduate students. It is common for students from other options in GPS, EAS, and CCE to work with ESE faculty as well.

We typically receive over 100 applications to the ESE program each year. The option gives each application a full review.

Preparation in one or more areas of science, engineering, or mathematics is a prerequisite. However, students in ESE come from all disciplines, including pure and applied mathematics, physics, chemistry, biology, atmospheric science, oceanography, mechanical engineering, chemical engineering, computer science, etc.

There are many routes to Caltech admission including some that are considered non-traditional. No matter your route, we admit students who have demonstrated, through their personal statement and/or prior experiences, that they are passionate about research and their decision to pursue a Ph.D. and who have the academic background needed to be successful at Caltech. For example, successful applicants may have a strong transcript in a curriculum that includes significant quantitative science, mathematics, and/or engineering coursework; evidence of previous research/scholarly experience; and strong letters of recommendation from those who know them well and can speak to their ability to be successful at Caltech. For more details, please review our admissions rubric.

There is a cost of $100 to apply to graduate school at Caltech. A fee waiver is available, and we encourage anyone for whom the fee represents a burden to apply for a waiver. The fee waiver is available within the online admissions system and is submitted to the Graduate Studies Office. If the fee, which supports the Graduate Studies Office in processing the applications, represents a burden, please request the waiver without concern.

Students are admitted to the ESE program through a decision by faculty committees; they are not admitted directly to work with individual faculty members. The number of new students faculty members accept in a given year is often in flux. Potential applicants may contact individual faculty members or other members of their research groups.

You are welcome to contact potential advisers, but admission offers to ESE are provided by faculty committees. You will be admitted to a Caltech program but not directly into a research group. During your first year in residence you will have an opportunity to work in several groups and find one that matches your interests. So, as you develop your application make sure to think about several groups that you would like to explore. It is helpful to the admissions committee to mention in your application letter those faculty members that you feel could be suitable advisers for your research interests. Some faculty members have dual appointments in different options (even divisions), so it is best to contact them individually if you are unsure which option to apply to. You can find a list of ESE faculty here.

The Statement of Purpose should reflect your reasoning for applying to the PhD program in Environmental Science and Engineering at Caltech. Things you can include in your statement are:

• your motivations, your research interests and why you feel that ESE would be a suitable fit; this could include any faculty with whom you would like to work;
• any previous personal, educational, research, or professional experiences that qualify you as a researcher;
• concrete examples of how you solved a challenging research or coursework problem;
• thoughts about your future career paths and why Caltech is a great choice for you; and
• any extenuating circumstances and how you have overcome any challenges that have impacted your career path thus far.

An ideal statement is brief (2 pages) and clearly written.

We recommend the submission of GRE scores but do not require it. We believe in letting every applicant showcase their academic and research success in whatever form that may take: research projects, competitions, exams, awards, experiences, etc. GRE scores can provide key information that may not be evident from other aspects of the application. We do not use GRE cutoffs or other quantitative rankings. We consider any submitted test scores as one aspect of academic achievement, but we take a holistic approach to our application evaluation.

Decisions are typically made by the end of January. We will provide information on the admission decision via email.

ESE holds an open house weekend for admitted prospective students in late February or early March. We generally provide support for the cost of flights and accommodation during the visit. We highly recommend that prospective students come to campus and interact with potential faculty advisors and their research groups, meet the other prospective students , and explore the campus and surrounding area. If you are unable to make it to the scheduled visit weekend, you can contact the graduate options manager Julie Lee to schedule an individual visit.

Deferrals can be granted on a case-by-case basis after the student has been officially admitted.

For further questions, you can reach out to the graduate options manager for GPS, Julie Lee.

Graduate students are paid a stipend of $45,000 a year (as of 2023-2024), this typically increases year-to-year to account for cost-of-living increases in Pasadena). In addition, the graduate student fellowships cover all tuition charges. Stipends are uniform across ESE and do not depend on whether the student is serving as a teaching assistant or not. Caltech also offers a subsidized health insurance plan that covers a majority of physical and mental health needs and it operates a health center on campus. There is also subsidized dental and vision insurance available.

You will receive your stipend payment at the end of every month (beginning with your first month at Caltech, typically October). Caltech offers subsidized housing (see next question) and subsidized health care (see previous question). If the initial costs are a barrier, you can apply for a New Graduate Student Start-Up (NGSS) Loan of $2,500 from Caltech, which is disbursed during orientation week and payments begin 6 months later. For further details, you can confidentially contact the Dean's Office or the graduate options manager for GPS, Julie Lee.

Yes, unfortunately. However, the stipend does adequately cover housing costs for students. Many students choose to live with roommates to reduce costs, as housing near campus can be expensive. Information about graduate housing in the Catalina apartments and other Caltech-owned and rent-controlled properties is available through Caltech Housing.

All ESE students are guaranteed funding through the department through the fall term of their second year. We are committed to funding students throughout their graduate career, which transitions to support organized by the faculty advisor in year 2 generally via federal and private research grants and contracts. We do encourage and support students to personally apply for external fellowships. Some of the more common ones include:

• AMS fellowship
• NSF Graduate Research Fellowship
• DOE Office of Science Graduate Fellowship
• National Defense Science & Engineering Graduate Fellowship
• Soros Fellowship for New Americans
• Future Investigators in NASA Earth and Space Science and Technology (FINESST)
• Hertz Foundation Fellowship

Assistance and advice for applying to fellowships is offered by the Caltech Fellowships Advising office.

Students complete their MS within two years. The average time to complete the PhD is 5.5 years. Almost all students finish within 6 years.

Yes. Graduate students in ESE are expected to serve as teaching assistants (TA) one term per year starting from their second year. Caltech is on the quarter system and has three "teaching" terms: fall, winter, and spring. Many of the classes ESE students TA are graduate level classes and are an excellent opportunity to hone your skills as an instructor.

If your recommenders are unable to write their letters in English or your transcript is not in English, please contact the graduate options manager for GPS, Julie Lee.

GPA is a Grade Point Average. We are experienced with scales from different countries, so there is nothing specific you need to do.

For non-native speakers, there is a language test requirement but you will have a choice between TOEFL, IELTS, Pearsons, or Duolingo. In addition, Caltech offers English as a second language (ESL) courses for those who might benefit from improving their English skills. If there are reasons why you can't take a language test, please contact the graduate options manager for GPS, Julie Lee and we will attempt to find an alternative solution, if required.

This varies by country of citizenship, but certain governments offer competitive fellowships that STEM students can support PhD studies. Eligibility of most US government fellowships only extend to US citizens or permanent residents, but there are some that are open to international students as well:

• Fulbright Foreign Student Program
• NASA FINESST

Ultimately the admissions committee is trying to assess your potential to excel as a researcher. Ask your recommenders to write about not their experience with you as a student in a classroom, but also about your skills as a researcher, your prior research experience, or how your skills in the classroom can translate into skills in the lab. Our admissions rubric provides advice on what aspects of the recommendation letters will be considered during the application process.

In most cases, before starting your PhD you will need to pay for a visa, SEVIS fee, and travel to Pasadena. If you use Caltech housing and health insurance, those costs can be paid later in the academic term, after you start receiving your stipend. If you need help with start-up expenses, you can apply for a New Graduate Student Start-Up (NGSS) Loan of US$2500 that is disbursed in person during orientation.