Two recent matters speak to the effort by Back Bay residents to define the kind of community in which they live. One has to do with the reconstruction of the Clarendon Street playground, the second with a proposed zoning change at 247 Commonwealth Avenue.

In the early 1970s, a group of Back Bay residents and then-state representative Barney Frank appealed to City Hall to make a trash-strewn and unsightly lot of land into a neighborhood park. Slated for future development, the proposal was at first dismissed. But after mounting pressure, including a march on City Hall, the city relented and a playground was built.

That playground, located at the corner of Commonwealth Avenue and Clarendon Street, has been derided by some as the “million dollar playground.” In fact, however, the playground has served to define who and what the Back Bay is, an effort that continues to this day.

For many residents, the playground is much more than a ‘tot lot,’ as the Parks Department calls it. It functions as a town common, a meeting place for friends, for parties, and for play. It has become the kind of place that creates a community and holds it together. One striking example of this is the extraordinary commitment of park users, who hold fund-raisers, cleanups and monitor the area daily.

But after years of use, it became time to update the equipment. Over the last year, residents met and planned the reconstruction of the park, including new equipment and landscaping. Recognizing the critical importance of the park to the neighborhood’s common life, they insisted upon a tight construction schedule that would allow it to reopen by the end of August.

It’s now almost mid-September, and work is not yet done. What happened? The apparent answer is that a combination of missteps occurred: the architect’s design plans were misdrawn, equipment was late in being delivered, and the city and contractor began arguing over the contractor’s contract and invoice payments. One guess is that construction won’t be completed until mid-October. Meanwhile, the entire community is hurt.

And what kind of community is that? It is one that is much like Boston’s other neighborhoods, one that is defined essentially by its residential character, not by its tourists. Maintaining that character is a constant struggle, however. Oftentimes, it seems, residents have a better sense of that character than city planning agencies. An example close at hand has to do with a zoning fight over the building at 247 Commonwealth Avenue.

247 Commonwealth Avenue had for years been the home of the American Cancer Society. The Society recently decided to move and proposed selling to the for-profit English Language School. To do so, however, required a zoning change to make the site commercial.

Residents argued that commercial zoning ran counter to the fundamental character of the street, which is residential. There are some long-standing exceptions to the residential zoning along Commonwealth Avenue (the restaurant Spasso is one of them), but in general the effort has been to enhance the Back Bay as a residential community. Indeed, allowing this particular building to become commercial appeared to open the door for others.

Despite a commitment to support the neighborhood, the Boston Redevelopment Authority, the city’s planning agency, reversed itself and said it would support commercial zoning. Then it flip-flopped again. Fortunately, residents showed up en masse, on a Tuesday morning in late August, to oppose the zoning change. After some debate, the neighborhood won by a 4-2 vote.

The vote on 247 Commonwealth Avenue was important, but it certainly will not be the last fight of its kind. Inevitably, there will be more zoning battles in the future. The current frustration with construction notwithstanding, the Clarendon Street playground will, eventually, reopen.

The efforts needed to build one’s community are a never-ending series of seemingly small skirmishes such as these.