Both sound great. Who doesn't want to be agile or lean? Furthermore, why would you have to choose between the two? When we're talking about software development, Pivotal Tracker puts all its chips behind one of these adjectives-turned-philosophies. But can the two approaches to software development, ultimately, coexist in the same business, project, or team?

First, let's define our terms. Thankfully, the labels for these methodologies are rather literal. Agile, which Pivotal Tracker stands firmly behind, allows teams of developers to be nimble in the iterative back-and-forth inherent in software development. Lean, much like a cut of expensive meat at the store, is relatively absent of fat, the unnecessary, unproductive parts of a process or business.

Both approaches aim to optimize workflow. Agile, broadly, emphasizes teamwork, multiple owners of a particular project domain, and a robust feedback loop. Lean, broadly, aims to trim the fat—if your time isn't spent making or optimizing the product, stop devoting your time to that particular task.

But what is lean?

Its founders, Mary and Tom Poppendieck, adapted these principles for lean software development from existing principles for old-school manufacturing. Like agile, it aims for quality, speed, and customer satisfaction. But if you could pick its primary operating principle, "eliminate waste" would be head and shoulders above the rest.

So far, so good. Work smarter, not harder. Create order, not chaos. All things, they say, budding businesses backed by top talent and VC must espouse early on.

Its critics have pointed out that plugging your ears to anything (and they mean anything) that does not contribute to the tasks at hand gives teams tunnel vision. Though specific tasks may be accomplished in the short or medium term, the broader picture isn't taken into account.

Abby Fichtner, aka Hacker Chick, argues that making sure every employee is busy 100% of the time actually incurs hefty costs.

"Knowledge degrades quickly, requirements get out of date, the feedback loop is delayed so we don't learn what we're doing wrong," she wrote in an analysis of agile vs. lean methodologies. The result is unfinished, untested, misunderstood, and often flat-out unnecessary code bogging down our product, degrading its quality, and actually slowing us down."

For example, Fichtner notes the difficulty in implementing features created so long ago no one remembers what it was for, or tracking down an error in the code that was created so long ago no one remembers how it came to be. She says that the only way to go faster is to optimize the whole. Identify whatever is slowing down the whole process or adding waste and remove those, rather than remaining 100% focused on achieving 100% optimized personnel or process.

That said: Is it possible to be both lean and agile?

Yes. Rather than thinking of lean and agile as apples and oranges or parallel lines that never cross, these aren't necessarily competing ideologies. Many companies, in fact, work under a hybrid of agile + [other methodology], vs. strictly one or another.

Author Dan Woods, writing for Forbes, predicted as much in 2010:

"Someone else can name this phenomenon, but lean and agile are merging," he said, noting that when connecting and considering the work of many different teams, agile methods in a lean framework may make more sense.

We explored some of the tangible overlap in this Venn diagram in a Pivotal Tracker blog post: a case study featuring Louisville, KY-based Humana. One of the decades-old company's newest business units is a Digital Experience Center (DEC), whose small, startup-like team is guided by agile principles.

The DEC, as explained by Product Manager Nick Hill, is primarily tasked with helping the rest of Humana's IT organization develop and test software more quickly and efficiently. The processes do and should sound familiar to those in both lean and agile circles.

Learn more about how lean software development has informed certain features of Pivotal Tracker, particularly with regard to lead time and cycle time for stories.