When Karimu founders Don Stoll and Marianne Kent-Stoll first went to Africa in 2007, as cultural tourists, northeastern Tanzania’s Ayalagaya Ward lacked clean water and had crumbling classrooms. Its people had to make do with a tiny and woefully inadequate dispensary. 


Today, visitors see plentiful clean water, renovated or brand-new school and medical buildings, and dynamic income programs that are unlocking the community's wealth potential. 


Change has come to Ayalagaya because Don and Marianne knew they could not turn their backs on people in need. They began modestly, donating five hundred dollars to build a simple latrine for Ufani Primary School, whose toilet facility — “still the worst we’ve ever seen,” Marianne recalls — was so bad that the Tanzanian government had threatened to shut the school down.  


It was Ufani’s Head Teacher, Paul Yoronimo, who asked Don and Marianne to return. Paul and other residents opened their eyes to the community’s many interrelated needs. They pointed out that even the brightest and most ambitious students would benefit little from school improvements if they were too sick to attend class or if their parents were too sick to work and therefore needed their children’s labor on their farms. And how could students hope for a better future if their parents lacked access to the financial services needed to move beyond subsistence farming? 


Don and Marianne founded Karimu in January 2008 with the goal of renovating and expanding Ufani Primary. But Karimu gradually became involved in addressing every development need pinpointed by the villagers. Its founders saw that the Tanzanians knew what they needed to better their lives but that they lacked the resources to make those improvements.  


Karimu began with Ufani School
First volunteer trip 2008 



By leading annual volunteer trips to Tanzania, Don and Marianne inspired other people to help. But at home in California they worked in secondary education and had limited access to donor funding. A breakthrough came in 2016. That year former Google Vice President Nelson Mattos and his wife Claudia, a designer and architect, joined the volunteer trip. They were impressed by the community’s efforts to improve their lives and by the depth of friendship and trust between the villagers and Don and Marianne. 


Nelson and Claudia had planned to found their own nonprofit. They believed that eliminating poverty requires an unwavering commitment to one region before moving on to another and that all the interrelated problems of poverty must be addressed in parallel. But the friendship and trust needed to ground a long-term commitment were already in place in Ayalagaya Ward, so they joined forces with Don and Marianne. Thanks to this partnership, Karimu has grown its annual fundraising capacity from between $50,000 and $100,000 to more than $1 million.


Nelson’s managerial expertise impacted Karimu right away. He hired and mentored Tanzanian staff to make sure that operations were grounded in the community and running year-round. He appointed Shau Erro Ae as Field Officer and Treasurer. Despite Shau’s youth — he was in his mid-twenties, in a culture that reveres age and experience — he soon became a prominent local figure, driving Karimu’s work forward even as the global pandemic put volunteer trips on hold. 


Karimu is now close to finishing a project to bring clean water to the fifteen thousand residents of Arri Ward, Ayalagaya’s neighbor. Over the course of fifteen years, Karimu has formed deep connections to the Tanzanian government, which Don, Marianne, Nelson, and Claudia believe will facilitate a dramatic impact in Arri more swiftly than in Ayalagaya. Entrepreneurial training, health interventions, professional development for teachers, and construction of classrooms and school bathrooms are already underway in Arri Ward.



In Arri Ward as in Ayalagaya, Karimu will continue to work holistically and respectfully with the community. Karimu will continue to insist that the community must commit to the maintenance of all projects so that these will benefit future generations. 

Karimu thanks the fifty-plus volunteers who give almost five thousand hours per year of their time, our staff in Tanzania, the Tanzanian government, and the people of Arri and Ayalagaya who are determined to uplift their community and see a better future for their children. 

Here is a timeline of the history of the Karimu from 2007 to 2023

Karimu begins with the renovation of Ufani Primary School. 


  • Founders Don and Marianne visit Ayalagaya as cultural tourists 

  • They donate $500 to finish latrines and keep Ufani Primary School from closing

2008 and 2009 

  • Karimu established as 501(c)(3) nonprofit

  • Volunteer trips begin

  • Ufani Primary School classrooms and teachers’ offices are completed


Karimu recognizes the interrelated problems of poverty and extends its reach to health education, water, sanitation, infrastructure, and financial services.

2010 to 2015

  • Donates medicine to Dared Kati Clinic, forms Kikundi Afya Mama na Mtoto (Group for Mother and Child   Health), facilitates health education for nurses and midwives, runs community workshop on hygiene and HIV prevention, distributes 10,000 malaria nets

  • Builds bathrooms, showers, and running water provided to Dareda Kati Clinic

  • Clean water brought to Ufani School and surrounding households

  • Clean water brought to Bacho Primary School and surrounding households 

  • Karimu partners with Bridging the Gap Africa to build walking bridge so that villagers are no longer cut off from services during rainy season 

  • Builds irrigation canal to control water to farmlands 

  • Brings electricity and internet to Ayalagaya Secondary 

  • Builds kitchen with fuel-efficient smoke-free stoves for Ayalagaya Secondary School

  • Karimu funds the formation of UFAGRO microlending group with the intention of expanding financial services

  • Launches professional development for teachers to enable them to obtain degrees through distance learning 

  • Ufani Primary School is completed and recognized by Tanzanian Government as a model school.  


Karimu is able to expand because Nelson and Claudia Mattos dedicate their energy and expertise to scaling projects. The elimination of poverty becomes a realistic goal.  

2016 to 2017  

  • New Dareda Kati Health clinic completed

  • Dareda Kati Clinic is honored by Uhuru (Freedom) Torch, symbolizing light and freedom throughout Tanzania and recognizing successful development projects 

  • New Chief Operating Officer Nelson Mattos hires Tanzanian staff and implements organizational systems. Shau Ero Ae becomes Karimu Field Officer and Treasurer. 

  • Begins top-to-bottom renovation of Bacho Primary School 

2,156 households now have clean water

Karimu completes its largest and most impactful project and becomes more strategic in organizational structure and execution of projects. 

2018 to 2019  

  • Completes project to bring clean water to all of Ayalagaya Ward’s 15,000 residents

  • First community-wide five-year strategic planning meeting for Ayalagaya Ward

  • Karimu establishes Tanzanian Board 

  • Chief Operating Officer implements processes and procedures for construction, maintenance, teacher scholarship programs, and MOU’s (Memorandums of Understanding) for all projects and programs

  • Finishes renovating Bacho Primary School

  • Builds bathrooms for Haysam and Gajal Primary School 

  • Continues the expansion of Ayalagaya Secondary School 

  • Conducts leadership training for Ayalagaya Secondary School girls

  • Ayalagaya Ward water project honored by Uhuru torch

  • Reconstruction of Bacho Primary School honored by Uhuru torch

2018--first community-wide strategic planning meeting 


Karimu partners with health officials to prevent COVID. With the absence of volunteers due to travel restrictions, Karimu employees take on a new level of leadership in COVID prevention campaign.

2020 to 2022                                                                               

  • Water tanks brought to all Arri Ward schools

  • COVID prevention supplies donated to all schools and clinics 

  • Builds Gajal Dispensary 

  • Builds housing for Dareda Kati Clinic nurses and doctor 

  • Supplies books to all Ayalagaya Ward schools 

  • Organizes computer training for teachers, still ongoing

  • Introduces vanilla farming and partners with NEI (Natural Extract Industries)


Karimu prepares to move into Arri Ward as financial services and income programs continue to provide pathways out of poverty for Ayalagaya Ward. 

2021 to 2022

  • Ayalagaya Secondary School expanded and improved to become high school 

  • Builds Ayalagaya student hostels 

  • Builds two classrooms for Arri Primary School, Dareda Kati Primary School, and Gajal Primary School 

  • Builds bathrooms for Tsaayo Secondary, Dohom Primary school, and Dareda Kati Primary School 

  • Provides seed money to the federation from which savings groups can take out larger loans which, in turn, will increase the loan funds available to their members. 

  • National dignitaries bring Uhuru Torch and national recognition plaque to Ayalagaya student hostels 

  • Dareda Kati Primary school recognized as third cleanest primary school in Tanzania

  • Karimu recognized as #1 NGO operating in Manyara Region

  • Dareda Kati Clinic upgraded to Health Center, accommodating extended stays and minor surgery 

  • Builds hostel for special-needs students 

  • Launches green bean pilot to penetrate European markets 

  • Eight savings groups are trained and join savings groups federation 

  • Twenty percent of Ayalagaya Ward households now belong to savings groups 

  • 28 students graduate from six-month entrepreneurial training course 

  • Ayalagaya High School honored as the third best performing school in Tanzania



  • Arri Water Project is underway— it consists of over 200 water points that will ensure clean water within 500 meters of each household due to be completed May 2023