Tworkov made a radical stylistic shift in the mid-1960s in an effort to distance himself from what he perceived as Abstract Expressionism’s forced spontaneity. During these years, he painted diagrammatic configurations spurred by a renewed interest in geometry and mathematics. Using the rectangle as a measurement tool and foundation of his compositions, Tworkov moved away from any reliance on automatism and turned to a methodical approach to the canvas.
He also looked to drawing for inspiration as he came to consider his paintings an extension of his draftsmanship. Blunt markings on paper appealed to him as a method of disrupting perceived illusionism which he heightened with a limited palette and layers of paint over and below delineated grids and geometric shapes. In 1967, during his tenure at Yale University, Tworkov began mixing liquitex with paint, to create a medium that he could build-up much like charcoal, which he felt had "the quality of keeping the shape of the stroke" that he painted. This allowed him to adapt charcoal drawings from as early as 1950 to the painted canvas. Tworkov’s focus on the relationship between points, lines and planes bolstered his sustained effort to maintain a flat surface, thus creating a diversity of compositional formats in his paintings from this period.
A forerunner of post-Minimalism, Tworkov entered the 1970s with a conceptual perspective towards painting that he used to create self-imposed rules and limits which he always balanced with a visible presence of the artist’s hand. In his compositions from the early 1970s Tworkov offered playful variations on numbering systems where the divisions within the canvas followed the Fibonacci sequence of 3:5:8. In mathematics, he found possibilities for experimentation within pre-determined systems, as seen in his use of diagonal and perpendicular delineations on canvas to create a constantly shifting tension between foreground and background.